8 files changed, 1479 insertions, 0 deletions
diff --git a/tools/cru-py/cru/_util/__init__.py b/tools/cru-py/cru/_util/__init__.py
new file mode 100644
index 0000000..481502c
--- /dev/null
+++ b/tools/cru-py/cru/_util/__init__.py
@@ -0,0 +1,63 @@
+from ._const import (
+    CruNotFound,
+    CruUseDefault,
+    CruDontChange,
+    CruNoValue,
+    CruPlaceholder,
+)
+from ._func import (
+    CruFunction,
+    CruFunctionMeta,
+    CruRawFunctions,
+    CruWrappedFunctions,
+    CruFunctionGenerators,
+)
+from ._list import (
+    CruList,
+    CruInplaceList,
+    CruUniqueKeyInplaceList,
+    ListOperations,
+    CanBeList,
+    ElementOperation,
+    ElementPredicate,
+    ElementTransformer,
+    OptionalElementOperation,
+    ElementPredicate,
+    OptionalElementTransformer,
+)
+from ._type import TypeSet
+
+F = CruFunction
+WF = CruWrappedFunctions
+FG = CruFunctionGenerators
+L = CruList
+
+
+__all__ = [
+    "CruNotFound",
+    "CruUseDefault",
+    "CruDontChange",
+    "CruNoValue",
+    "CruPlaceholder",
+    "CruFunction",
+    "CruFunctionMeta",
+    "CruRawFunctions",
+    "CruWrappedFunctions",
+    "CruFunctionGenerators",
+    "CruList",
+    "CruInplaceList",
+    "CruUniqueKeyInplaceList",
+    "ListOperations",
+    "CanBeList",
+    "ElementOperation",
+    "ElementPredicate",
+    "ElementTransformer",
+    "OptionalElementOperation",
+    "ElementPredicate",
+    "OptionalElementTransformer",
+    "TypeSet",
+    "F",
+    "WF",
+    "FG",
+    "L",
+]
diff --git a/tools/cru-py/cru/_util/_const.py b/tools/cru-py/cru/_util/_const.py
new file mode 100644
index 0000000..bc02c3a
--- /dev/null
+++ b/tools/cru-py/cru/_util/_const.py
@@ -0,0 +1,49 @@
+from enum import Enum, auto
+from typing import Self, TypeGuard, TypeVar
+
+from ._cru import CRU
+
+_T = TypeVar("_T")
+
+
+class CruConstantBase(Enum):
+    @classmethod
+    def check(cls, v: _T | Self) -> TypeGuard[Self]:
+        return isinstance(v, cls)
+
+    @classmethod
+    def check_not(cls, v: _T | Self) -> TypeGuard[_T]:
+        return not cls.check(v)
+
+    @classmethod
+    def value(cls) -> Self:
+        return cls.VALUE  # type: ignore
+
+
+class CruNotFound(CruConstantBase):
+    VALUE = auto()
+
+
+class CruUseDefault(CruConstantBase):
+    VALUE = auto()
+
+
+class CruDontChange(CruConstantBase):
+    VALUE = auto()
+
+
+class CruNoValue(CruConstantBase):
+    VALUE = auto()
+
+
+class CruPlaceholder(CruConstantBase):
+    VALUE = auto()
+
+
+CRU.add_objects(
+    CruNotFound,
+    CruUseDefault,
+    CruDontChange,
+    CruNoValue,
+    CruPlaceholder,
+)
diff --git a/tools/cru-py/cru/_util/_cru.py b/tools/cru-py/cru/_util/_cru.py
new file mode 100644
index 0000000..0085a80
--- /dev/null
+++ b/tools/cru-py/cru/_util/_cru.py
@@ -0,0 +1,94 @@
+from typing import Any
+
+from ._lang import remove_none
+
+
+class _Cru:
+    NAME_PREFIXES = ("CRU_", "Cru", "cru_")
+
+    def __init__(self) -> None:
+        self._d: dict[str, Any] = {}
+
+    def all_names(self) -> list[str]:
+        return list(self._d.keys())
+
+    def get(self, name: str) -> Any:
+        return self._d[name]
+
+    def has_name(self, name: str) -> bool:
+        return name in self._d
+
+    @staticmethod
+    def _maybe_remove_prefix(name: str) -> str | None:
+        for prefix in _Cru.NAME_PREFIXES:
+            if name.startswith(prefix):
+                return name[len(prefix) :]
+        return None
+
+    def _check_name_exist(self, *names: str | None) -> None:
+        for name in names:
+            if name is None:
+                continue
+            if self.has_name(name):
+                raise ValueError(f"Name {name} exists in CRU.")
+
+    @staticmethod
+    def check_name_format(name: str) -> tuple[str, str]:
+        no_prefix_name = _Cru._maybe_remove_prefix(name)
+        if no_prefix_name is None:
+            raise ValueError(f"Name {name} is not prefixed with {_Cru.NAME_PREFIXES}.")
+        return name, no_prefix_name
+
+    @staticmethod
+    def _check_object_name(o) -> tuple[str, str]:
+        return _Cru.check_name_format(o.__name__)
+
+    def _do_add(self, o, *names: str | None) -> list[str]:
+        name_list: list[str] = remove_none(names)
+        for name in name_list:
+            self._d[name] = o
+        return name_list
+
+    def add(self, o, name: str | None) -> tuple[str, str | None]:
+        no_prefix_name: str | None
+        if name is None:
+            name, no_prefix_name = self._check_object_name(o)
+        else:
+            no_prefix_name = self._maybe_remove_prefix(name)
+
+        self._check_name_exist(name, no_prefix_name)
+        self._do_add(o, name, no_prefix_name)
+        return name, no_prefix_name
+
+    def add_with_alias(self, o, name: str | None = None, *aliases: str) -> list[str]:
+        final_names: list[str | None] = []
+        no_prefix_name: str | None
+        if name is None:
+            name, no_prefix_name = self._check_object_name(o)
+            self._check_name_exist(name, no_prefix_name)
+            final_names.extend([name, no_prefix_name])
+        for alias in aliases:
+            no_prefix_name = self._maybe_remove_prefix(alias)
+            self._check_name_exist(alias, no_prefix_name)
+            final_names.extend([alias, no_prefix_name])
+
+        return self._do_add(o, *final_names)
+
+    def add_objects(self, *objects):
+        final_list = []
+        for o in objects:
+            name, no_prefix_name = self._check_object_name(o)
+            self._check_name_exist(name, no_prefix_name)
+            final_list.append((o, name, no_prefix_name))
+        for o, name, no_prefix_name in final_list:
+            self._do_add(o, name, no_prefix_name)
+
+    def __getitem__(self, item):
+        return self.get(item)
+
+    def __getattr__(self, item):
+        return self.get(item)
+
+
+CRU_NAME_PREFIXES = _Cru.NAME_PREFIXES
+CRU = _Cru()
diff --git a/tools/cru-py/cru/_util/_event.py b/tools/cru-py/cru/_util/_event.py
new file mode 100644
index 0000000..813e33f
--- /dev/null
+++ b/tools/cru-py/cru/_util/_event.py
@@ -0,0 +1,41 @@
+from typing import ParamSpec, TypeVar, Callable
+
+from ._list import CruInplaceList, CruList
+
+P = ParamSpec('P')
+R = TypeVar('R')
+F = Callable[P, R]
+
+
+class EventHandlerToken:
+    def __init__(self, event: "Event", handler: F, once: bool = False) -> None:
+        self._event = event
+        self._handler = handler
+        self._once = once
+
+    @property
+    def event(self) -> "Event":
+        return self._event
+
+    @property
+    def handler(self) -> F:
+        return self._handler
+
+    @property
+    def once(self) -> bool:
+        return self._once
+
+
+class Event:
+    def __init__(self, name: str) -> None:
+        self._name = name
+        self._tokens: CruInplaceList[EventHandlerToken] = CruInplaceList()
+
+    def register(self, handler: F, once: bool = False) -> EventHandlerToken:
+        token = EventHandlerToken(self, handler, once)
+        self._tokens.append(token)
+        return token
+
+    def unregister(self, *h: EventHandlerToken | F) -> int:
+
+        self._tokens.find_all_indices_if(lambda t: )
diff --git a/tools/cru-py/cru/_util/_func.py b/tools/cru-py/cru/_util/_func.py
new file mode 100644
index 0000000..0b8b07a
--- /dev/null
+++ b/tools/cru-py/cru/_util/_func.py
@@ -0,0 +1,259 @@
+from __future__ import annotations
+
+from collections.abc import Callable
+from enum import Flag, auto
+from typing import (
+    Any,
+    Generic,
+    Iterable,
+    Literal,
+    ParamSpec,
+    TypeAlias,
+    TypeVar,
+    cast,
+)
+
+from ._cru import CRU
+from ._const import CruPlaceholder
+
+_P = ParamSpec("_P")
+_T = TypeVar("_T")
+
+
+class CruRawFunctions:
+    @staticmethod
+    def none(*_v, **_kwargs) -> None:
+        return None
+
+    @staticmethod
+    def true(*_v, **_kwargs) -> Literal[True]:
+        return True
+
+    @staticmethod
+    def false(*_v, **_kwargs) -> Literal[False]:
+        return False
+
+    @staticmethod
+    def identity(v: _T) -> _T:
+        return v
+
+    @staticmethod
+    def only_you(v: _T, *_v, **_kwargs) -> _T:
+        return v
+
+    @staticmethod
+    def equal(a: Any, b: Any) -> bool:
+        return a == b
+
+    @staticmethod
+    def not_equal(a: Any, b: Any) -> bool:
+        return a != b
+
+    @staticmethod
+    def not_(v: Any) -> Any:
+        return not v
+
+
+CruArgsChainableCallable: TypeAlias = Callable[..., Iterable[Any]]
+CruKwargsChainableCallable: TypeAlias = Callable[..., Iterable[tuple[str, Any]]]
+CruChainableCallable: TypeAlias = Callable[
+    ..., tuple[Iterable[Any], Iterable[tuple[str, Any]]]
+]
+
+
+class CruFunctionChainMode(Flag):
+    ARGS = auto()
+    KWARGS = auto()
+    BOTH = ARGS | KWARGS
+
+
+class CruFunctionMeta:
+    @staticmethod
+    def bind(func: Callable[..., _T], *bind_args, **bind_kwargs) -> Callable[..., _T]:
+        def bound_func(*args, **kwargs):
+            popped = 0
+            real_args = []
+            for arg in bind_args:
+                if CruPlaceholder.check(arg):
+                    real_args.append(args[popped])
+                    popped += 1
+                else:
+                    real_args.append(arg)
+            real_args.extend(args[popped:])
+            return func(*real_args, **(bind_kwargs | kwargs))
+
+        return bound_func
+
+    @staticmethod
+    def chain_with_args(
+        funcs: Iterable[CruArgsChainableCallable], *bind_args, **bind_kwargs
+    ) -> CruArgsChainableCallable:
+        def chained_func(*args):
+            for func in funcs:
+                args = CruFunctionMeta.bind(func, *bind_args, **bind_kwargs)(*args)
+            return args
+
+        return chained_func
+
+    @staticmethod
+    def chain_with_kwargs(
+        funcs: Iterable[CruKwargsChainableCallable], *bind_args, **bind_kwargs
+    ) -> CruKwargsChainableCallable:
+        def chained_func(**kwargs):
+            for func in funcs:
+                kwargs = CruFunctionMeta.bind(func, *bind_args, **bind_kwargs)(**kwargs)
+            return kwargs
+
+        return chained_func
+
+    @staticmethod
+    def chain_with_both(
+        funcs: Iterable[CruChainableCallable], *bind_args, **bind_kwargs
+    ) -> CruChainableCallable:
+        def chained_func(*args, **kwargs):
+            for func in funcs:
+                args, kwargs = CruFunctionMeta.bind(func, *bind_args, **bind_kwargs)(
+                    *args, **kwargs
+                )
+            return args, kwargs
+
+        return chained_func
+
+    @staticmethod
+    def chain(
+        mode: CruFunctionChainMode,
+        funcs: Iterable[
+            CruArgsChainableCallable | CruKwargsChainableCallable | CruChainableCallable
+        ],
+        *bind_args,
+        **bind_kwargs,
+    ) -> CruArgsChainableCallable | CruKwargsChainableCallable | CruChainableCallable:
+        if mode == CruFunctionChainMode.ARGS:
+            return CruFunctionMeta.chain_with_args(
+                cast(Iterable[CruArgsChainableCallable], funcs),
+                *bind_args,
+                **bind_kwargs,
+            )
+        elif mode == CruFunctionChainMode.KWARGS:
+            return CruFunctionMeta.chain_with_kwargs(
+                cast(Iterable[CruKwargsChainableCallable], funcs),
+                *bind_args,
+                **bind_kwargs,
+            )
+        elif mode == CruFunctionChainMode.BOTH:
+            return CruFunctionMeta.chain_with_both(
+                cast(Iterable[CruChainableCallable], funcs), *bind_args, **bind_kwargs
+            )
+
+
+# Advanced Function Wrapper
+class CruFunction(Generic[_P, _T]):
+
+    def __init__(self, f: Callable[_P, _T]):
+        self._f = f
+
+    @property
+    def f(self) -> Callable[_P, _T]:
+        return self._f
+
+    @property
+    def func(self) -> Callable[_P, _T]:
+        return self.f
+
+    def bind(self, *bind_args, **bind_kwargs) -> CruFunction[..., _T]:
+        self._f = CruFunctionMeta.bind(self._f, *bind_args, **bind_kwargs)
+        return self
+
+    def _iter_with_self(
+        self, funcs: Iterable[Callable[..., Any]]
+    ) -> Iterable[Callable[..., Any]]:
+        yield self
+        yield from funcs
+
+    @staticmethod
+    def chain_with_args(
+        self,
+        funcs: Iterable[CruArgsChainableCallable],
+        *bind_args,
+        **bind_kwargs,
+    ) -> CruArgsChainableCallable:
+        return CruFunction(
+            CruFunctionMeta.chain_with_args(
+                self._iter_with_self(funcs), *bind_args, **bind_kwargs
+            )
+        )
+
+    def chain_with_kwargs(
+        self, funcs: Iterable[CruKwargsChainableCallable], *bind_args, **bind_kwargs
+    ) -> CruKwargsChainableCallable:
+        return CruFunction(
+            CruFunctionMeta.chain_with_kwargs(
+                self._iter_with_self(funcs), *bind_args, **bind_kwargs
+            )
+        )
+
+    def chain_with_both(
+        self, funcs: Iterable[CruChainableCallable], *bind_args, **bind_kwargs
+    ) -> CruChainableCallable:
+        return CruFunction(
+            CruFunctionMeta.chain_with_both(
+                self._iter_with_self(funcs), *bind_args, **bind_kwargs
+            )
+        )
+
+    def chain(
+        self,
+        mode: CruFunctionChainMode,
+        funcs: Iterable[
+            CruArgsChainableCallable | CruKwargsChainableCallable | CruChainableCallable
+        ],
+        *bind_args,
+        **bind_kwargs,
+    ) -> CruArgsChainableCallable | CruKwargsChainableCallable | CruChainableCallable:
+        return CruFunction(
+            CruFunctionMeta.chain(
+                mode, self._iter_with_self(funcs), *bind_args, **bind_kwargs
+            )
+        )
+
+    def __call__(self, *args: _P.args, **kwargs: _P.kwargs) -> _T:
+        return self._f(*args, **kwargs)
+
+    @staticmethod
+    def make_chain(
+        mode: CruFunctionChainMode,
+        funcs: Iterable[
+            CruArgsChainableCallable | CruKwargsChainableCallable | CruChainableCallable
+        ],
+        *bind_args,
+        **bind_kwargs,
+    ) -> CruFunction:
+        return CruFunction(
+            CruFunctionMeta.chain(mode, funcs, *bind_args, **bind_kwargs)
+        )
+
+
+class CruWrappedFunctions:
+    none = CruFunction(CruRawFunctions.none)
+    true = CruFunction(CruRawFunctions.true)
+    false = CruFunction(CruRawFunctions.false)
+    identity = CruFunction(CruRawFunctions.identity)
+    only_you = CruFunction(CruRawFunctions.only_you)
+    equal = CruFunction(CruRawFunctions.equal)
+    not_equal = CruFunction(CruRawFunctions.not_equal)
+    not_ = CruFunction(CruRawFunctions.not_)
+
+
+class CruFunctionGenerators:
+    @staticmethod
+    def make_isinstance_of_types(*types: type) -> Callable:
+        return CruFunction(lambda v: type(v) in types)
+
+
+CRU.add_objects(
+    CruRawFunctions,
+    CruFunctionMeta,
+    CruFunction,
+    CruWrappedFunctions,
+    CruFunctionGenerators,
+)
diff --git a/tools/cru-py/cru/_util/_lang.py b/tools/cru-py/cru/_util/_lang.py
new file mode 100644
index 0000000..925ba00
--- /dev/null
+++ b/tools/cru-py/cru/_util/_lang.py
@@ -0,0 +1,16 @@
+from collections.abc import Callable
+from typing import Any, Iterable, TypeVar, cast
+
+T = TypeVar("T")
+D = TypeVar("D")
+
+
+def remove_element(
+    iterable: Iterable[T | None], to_rm: Iterable[Any], des: type[D] | None = None
+) -> D:
+    to_rm = set(to_rm)
+    return cast(Callable[..., D], des or list)(v for v in iterable if v not in to_rm)
+
+
+def remove_none(iterable: Iterable[T | None], des: type[D] | None = None) -> D:
+    return cast(Callable[..., D], des or list)(v for v in iterable if v is not None)
diff --git a/tools/cru-py/cru/_util/_list.py b/tools/cru-py/cru/_util/_list.py
new file mode 100644
index 0000000..711d5f1
--- /dev/null
+++ b/tools/cru-py/cru/_util/_list.py
@@ -0,0 +1,915 @@
+from __future__ import annotations
+
+from collections.abc import Iterable, Callable
+from dataclasses import dataclass
+from enum import Enum
+from typing import (
+    Generator,
+    Literal,
+    Self,
+    TypeAlias,
+    TypeVar,
+    ParamSpec,
+    Any,
+    Generic,
+    ClassVar,
+    Optional,
+    Union,
+    assert_never,
+    cast,
+    overload,
+    override,
+)
+
+from ._const import CruNoValue, CruNotFound
+
+P = ParamSpec("P")
+T = TypeVar("T")
+O = TypeVar("O")
+F = TypeVar("F")
+
+CanBeList: TypeAlias = Iterable[T] | T | None
+
+OptionalIndex: TypeAlias = int | None
+OptionalType: TypeAlias = type | None
+ElementOperation: TypeAlias = Callable[[T], Any]
+ElementPredicate: TypeAlias = Callable[[T], bool]
+ElementTransformer: TypeAlias = Callable[[T], O]
+SelfElementTransformer: TypeAlias = ElementTransformer[T, T]
+AnyElementTransformer: TypeAlias = ElementTransformer[Any, Any]
+
+
+def flatten_with_func(
+    o: T,
+    max_depth: int,
+    is_leave: ElementPredicate[T],
+    get_children: ElementTransformer[T, Iterable[T]],
+    depth: int = 0,
+) -> Iterable[T]:
+    if depth == max_depth or is_leave(o):
+        yield o
+        return
+    for child in get_children(o):
+        yield from flatten_with_func(
+            child, max_depth, is_leave, get_children, depth + 1
+        )
+
+
+class _StepActionKind(Enum):
+    SKIP = 0
+    # TODO: Rename this
+    SEND = 1
+    STOP = 2
+    AGGREGATE = 3
+
+
+@dataclass
+class _StepAction(Generic[T]):
+    value: Iterable[_StepAction[T]] | T | None
+    kind: _StepActionKind
+
+    @property
+    def non_aggregate_value(self) -> T:
+        assert self.kind != _StepActionKind.AGGREGATE
+        return cast(T, self.value)
+
+    @staticmethod
+    def skip() -> _StepAction[T]:
+        return _StepAction(None, _StepActionKind.SKIP)
+
+    @staticmethod
+    def send(value: T | None) -> _StepAction[T]:
+        return _StepAction(value, _StepActionKind.SEND)
+
+    @staticmethod
+    def stop(value: T | None = None) -> _StepAction[T]:
+        return _StepAction(value, _StepActionKind.STOP)
+
+    @staticmethod
+    def aggregate(*results: _StepAction[T]) -> _StepAction[T]:
+        return _StepAction(results, _StepActionKind.AGGREGATE)
+
+    @staticmethod
+    def send_last(value: Any) -> _StepAction[T]:
+        return _StepAction.aggregate(_StepAction.send(value), _StepAction.stop())
+
+    def flatten(self) -> Iterable[_StepAction[T]]:
+        return flatten_with_func(
+            self,
+            -1,
+            lambda r: r.kind != _StepActionKind.AGGREGATE,
+            lambda r: cast(Iterable[_StepAction[T]], r.value),
+        )
+
+
+_r_skip = _StepAction.skip
+_r_send = _StepAction.send
+_r_stop = _StepAction.stop
+_r_send_last = _StepAction.send_last
+_r_aggregate = _StepAction.aggregate
+
+
+_GeneralStepAction: TypeAlias = _StepAction[T] | T | None
+_GeneralStepActionConverter: TypeAlias = Callable[
+    [_GeneralStepAction[T]], _StepAction[T]
+]
+_IterateOperation = Callable[[T, int], _GeneralStepAction[O]]
+_IteratePreHook = Callable[[Iterable[T]], _GeneralStepAction[O]]
+_IteratePostHook = Callable[[int], _GeneralStepAction[O]]
+
+
+class CruGenericIterableMeta:
+    StepActionKind = _StepActionKind
+    StepAction = _StepAction
+    GeneralStepAction = _GeneralStepAction
+    GeneralStepActionConverter = _GeneralStepActionConverter
+    IterateOperation = _IterateOperation
+    IteratePreHook = _IteratePreHook
+    IteratePostHook = _IteratePostHook
+
+    @staticmethod
+    def _non_result_to_send(value: O | None) -> _StepAction[O]:
+        return _StepAction.send(value)
+
+    @staticmethod
+    def _non_result_to_stop(value: O | None) -> _StepAction[O]:
+        return _StepAction.stop(value)
+
+    @staticmethod
+    def _none_pre_iterate() -> _StepAction[O]:
+        return _r_skip()
+
+    @staticmethod
+    def _none_post_iterate(
+        _index: int,
+    ) -> _StepAction[O]:
+        return _r_skip()
+
+    def iterate(
+        self,
+        operation: _IterateOperation[T, O],
+        fallback_return: O,
+        pre_iterate: _IteratePreHook[T, O],
+        post_iterate: _IteratePostHook[O],
+        convert_non_result: Callable[[O | None], _StepAction[O]],
+    ) -> Generator[O, None, O]:
+        pre_result = pre_iterate(self._iterable)
+        if not isinstance(pre_result, _StepAction):
+            real_pre_result = convert_non_result(pre_result)
+        for r in real_pre_result.flatten():
+            if r.kind == _StepActionKind.STOP:
+                return r.non_aggregate_value
+            elif r.kind == _StepActionKind.SEND:
+                yield r.non_aggregate_value
+
+        for index, element in enumerate(self._iterable):
+            result = operation(element, index)
+            if not isinstance(result, _StepAction):
+                real_result = convert_non_result(result)
+            for r in real_result.flatten():
+                if r.kind == _StepActionKind.STOP:
+                    return r.non_aggregate_value
+                elif r.kind == _StepActionKind.SEND:
+                    yield r.non_aggregate_value
+                else:
+                    continue
+
+        post_result = post_iterate(index + 1)
+        if not isinstance(post_result, _StepAction):
+            real_post_result = convert_non_result(post_result)
+        for r in real_post_result.flatten():
+            if r.kind == _StepActionKind.STOP:
+                return r.non_aggregate_value
+            elif r.kind == _StepActionKind.SEND:
+                yield r.non_aggregate_value
+
+        return fallback_return
+
+    def _new(
+        self,
+        operation: _IterateOperation,
+        fallback_return: O,
+        /,
+        pre_iterate: _IteratePreHook[T, O] | None = None,
+        post_iterate: _IteratePostHook[O] | None = None,
+    ) -> CruIterableWrapper:
+        return CruIterableWrapper(
+            self.iterate(
+                operation,
+                fallback_return,
+                pre_iterate or CruIterableWrapper._none_pre_iterate,
+                post_iterate or CruIterableWrapper._none_post_iterate,
+                CruIterableWrapper._non_result_to_send,
+            ),
+            self._create_new_upstream(),
+        )
+
+    def _result(
+        self,
+        operation: _IterateOperation,
+        fallback_return: O,
+        /,
+        result_transform: SelfElementTransformer[O] | None = None,
+        pre_iterate: _IteratePreHook[T, O] | None = None,
+        post_iterate: _IteratePostHook[O] | None = None,
+    ) -> O:
+        try:
+            for _ in self.iterate(
+                operation,
+                fallback_return,
+                pre_iterate or CruIterableWrapper._none_pre_iterate,
+                post_iterate or CruIterableWrapper._none_post_iterate,
+                CruIterableWrapper._non_result_to_stop,
+            ):
+                pass
+        except StopIteration as stop:
+            return (
+                stop.value if result_transform is None else result_transform(stop.value)
+            )
+        raise RuntimeError("Should not reach here")
+
+
+class IterDefaultResults:
+    @staticmethod
+    def true(_):
+        return True
+
+    @staticmethod
+    def false(_):
+        return False
+
+    @staticmethod
+    def not_found(_):
+        return CruNotFound.VALUE
+
+
+class CruIterableCreators:
+    @staticmethod
+    def with_(o: Any) -> CruIterableWrapper:
+        return CruIterableWrapper(iter(o))
+
+    @staticmethod
+    def empty() -> CruIterableWrapper:
+        return CruIterableCreators.with_([])
+
+    @staticmethod
+    def range(
+        a,
+        b=None,
+        c=None,
+    ) -> CruIterableWrapper[int]:
+        args = [arg for arg in [a, b, c] if arg is not None]
+        return CruIterableCreators.with_(range(*args))
+
+    @staticmethod
+    def unite(*args: T) -> CruIterableWrapper[T]:
+        return CruIterableCreators.with_(args)
+
+    @staticmethod
+    def _concat(*iterables: Iterable) -> Iterable:
+        for iterable in iterables:
+            yield from iterable
+
+    @staticmethod
+    def concat(*iterables: Iterable) -> CruIterableWrapper:
+        return CruIterableWrapper(CruIterableCreators._concat(*iterables))
+
+
+class CruIterableWrapper(Generic[T]):
+
+    def __init__(
+        self,
+        iterable: Iterable[T],
+    ) -> None:
+        self._iterable = iterable
+
+    def __iter__(self):
+        return self._iterable.__iter__()
+
+    @property
+    def me(self) -> Iterable[T]:
+        return self._iterable
+
+    def replace_me_with(self, iterable: Iterable[O]) -> CruIterableWrapper[O]:
+        return CruIterableCreators.with_(iterable)
+
+    def replace_me_with_empty(self) -> CruIterableWrapper[O]:
+        return CruIterableCreators.empty()
+
+    def replace_me_with_range(self, a, b=None, c=None) -> CruIterableWrapper[int]:
+        return CruIterableCreators.range(a, b, c)
+
+    def replace_me_with_unite(self, *args: O) -> CruIterableWrapper[O]:
+        return CruIterableCreators.unite(*args)
+
+    def replace_me_with_concat(self, *iterables: Iterable) -> CruIterableWrapper:
+        return CruIterableCreators.concat(*iterables)
+
+    @staticmethod
+    def _make_set(iterable: Iterable[O], discard: Iterable[Any] | None) -> set[O]:
+        s = set(iterable)
+        if discard is not None:
+            s = s - set(discard)
+        return s
+
+    @staticmethod
+    def _make_list(iterable: Iterable[O], discard: Iterable[Any] | None) -> list[O]:
+        if discard is None:
+            return list(iterable)
+        return [v for v in iterable if v not in discard]
+
+    def _help_make_set(
+        self, iterable: Iterable[O], discard: Iterable[Any] | None
+    ) -> set[O]:
+        return CruIterableWrapper._make_set(iterable, discard)
+
+    def _help_make_list(
+        self, iterable: Iterable[O], discard: Iterable[Any] | None
+    ) -> list[O]:
+        return CruIterableWrapper._make_list(iterable, discard)
+
+    def to_set(self, discard: Iterable[Any] | None = None) -> set[T]:
+        return CruIterableWrapper._make_set(self.me, discard)
+
+    def to_list(self, discard: Iterable[Any] | None = None) -> list[T]:
+        return CruIterableWrapper._make_list(self.me, discard)
+
+    def copy(self) -> CruIterableWrapper:
+        return CruIterableWrapper(iter(self.to_list()), self._create_new_upstream())
+
+    def new_start(
+        self, other: Iterable[O], /, clear_upstream: bool = False
+    ) -> CruIterableWrapper[O]:
+        return CruIterableWrapper(
+            other, None if clear_upstream else self._create_new_upstream()
+        )
+
+    @overload
+    def concat(self) -> Self: ...
+
+    @overload
+    def concat(
+        self, *iterable: Iterable[Any], last: Iterable[O]
+    ) -> CruIterableWrapper[O]: ...
+
+    def concat(self, *iterable: Iterable[Any]) -> CruIterableWrapper[Any]:  # type: ignore
+        return self.new_start(CruIterableCreators.concat(self.me, *iterable))
+
+    def all(self, predicate: ElementPredicate[T]) -> bool:
+        """
+        partial
+        """
+        return self._result(lambda v, _: predicate(v) and None, IterDefaultResults.true)
+
+    def all_isinstance(self, *types: OptionalType) -> bool:
+        """
+        partial
+        """
+        types = self._help_make_set(types)
+        return self.all(lambda v: type(v) in types)
+
+    def any(self, predicate: ElementPredicate[T]) -> bool:
+        """
+        partial
+        """
+        return self._result(lambda v, _: predicate(v) or None, IterDefaultResults.false)
+
+    def number(self) -> CruIterableWrapper:
+        """
+        partial
+        """
+        return self._new(lambda _, i: i)
+
+    def take(self, predicate: ElementPredicate[T]) -> CruIterableWrapper:
+        """
+        complete
+        """
+        return self._new(lambda v, _: _r_send(v) if predicate(v) else None)
+
+    def transform(
+        self, *transformers: OptionalElementTransformer
+    ) -> CruIterableWrapper:
+        """
+        complete
+        """
+
+        def _transform_element(element, _):
+            for transformer in self._help_make_list(transformers):
+                if transformer is not None:
+                    element = transformer(element)
+            return _r_send(element)
+
+        return self._new(_transform_element)
+
+    def take_n(self, max_count: int, neg_is_clone: bool = True) -> CruIterableWrapper:
+        """
+        partial
+        """
+        if max_count < 0:
+            if neg_is_clone:
+                return self.clone_me()
+            else:
+                raise ValueError("max_count must be 0 or positive.")
+        elif max_count == 0:
+            return self.drop_all()
+        return self._new(
+            lambda v, i: _r_send(v) if i < max_count - 1 else _r_send_last(v)
+        )
+
+    def take_by_indices(self, *indices: OptionalIndex) -> CruIterableWrapper:
+        """
+        partial
+        """
+        indices = self._help_make_set(indices)
+        max_index = max(indices)
+        return self.take_n(max_index + 1)._new(
+            lambda v, i: _r_send(v) if i in indices else None
+        )
+
+    def single_or(
+        self, fallback: Any | None = CRU_NOT_FOUND
+    ) -> T | Any | CRU_NOT_FOUND:
+        """
+        partial
+        """
+        first_2 = self.take_n(2)
+        has_value = False
+        value = None
+        for element in first_2.me:
+            if has_value:
+                raise ValueError("More than one value found.")
+            has_value = True
+            value = element
+        if has_value:
+            return value
+        else:
+            return fallback
+
+    def first_or(
+        self, predicate: ElementPredicate[T], fallback: Any | None = CRU_NOT_FOUND
+    ) -> T | CRU_NOT_FOUND:
+        """
+        partial
+        """
+        result_iterable = self.take_n(1).single_or()
+
+    @staticmethod
+    def first_index(
+        iterable: Iterable[T], predicate: ElementPredicate[T]
+    ) -> int | CRU_NOT_FOUND:
+        """
+        partial
+        """
+        for index, element in enumerate(iterable):
+            if predicate(element):
+                return index
+
+    @staticmethod
+    def take_indices(
+        iterable: Iterable[T], predicate: ElementPredicate[T]
+    ) -> Iterable[int]:
+        """
+        complete
+        """
+        for index, element in enumerate(iterable):
+            if predicate(element):
+                yield index
+
+    @staticmethod
+    def flatten(
+        o,
+        max_depth=-1,
+        is_leave: ElementPredicate | None = None,
+        get_children: OptionalElementTransformer = None,
+    ) -> Iterable:
+        """
+        complete
+        """
+        if is_leave is None:
+            is_leave = lambda v: not isinstance(v, Iterable)
+        if get_children is None:
+            get_children = lambda v: v
+        return CruIterableWrapper._flatten_with_func(
+            o, max_depth, is_leave, get_children
+        )
+
+    @staticmethod
+    def skip_by_indices(iterable: Iterable[T], *indices: OptionalIndex) -> Iterable[T]:
+        """
+        complete
+        """
+        indices = set(indices) - {None}
+        for index, element in enumerate(iterable):
+            if index not in indices:
+                yield element
+
+    @staticmethod
+    def skip_if(iterable: Iterable[T], predicate: ElementPredicate[T]) -> list[T]:
+        """
+        complete
+        """
+        for element in iterable:
+            if not predicate(element):
+                yield element
+
+    def drop_all(self) -> CruIterableWrapper:
+        return self.replace_me_with_empty()
+
+    @staticmethod
+    def remove_all_if(l: Iterable[T], p: ElementPredicate[T]) -> list[T]:
+        return [v for v in l if not p(v)]
+
+    @staticmethod
+    def remove_all_value(l: Iterable[T], *r: Any) -> list[T]:
+        return [v for v in l if v not in r]
+
+    @staticmethod
+    def replace_all_value(l: Iterable[T], old_value: Any, new_value: R) -> list[T | R]:
+        return [new_value if v == old_value else v for v in l]
+
+    @staticmethod
+    def foreach(iterable: Iterable[T], *f: OptionalElementOperation[T]) -> None:
+        if len(f) == 0:
+            return
+        for v in iterable:
+            for f_ in f:
+                if f_ is not None:
+                    f_(v)
+
+    @staticmethod
+    def make(v: CanBeList[T], /, none_to_empty_list: bool = True) -> list[T]:
+        if v is None and none_to_empty_list:
+            return []
+        return list(v) if isinstance(v, Iterable) else [v]
+
+
+class ListOperations:
+    @staticmethod
+    def all(iterable: Iterable[T], predicate: ElementPredicate[T]) -> bool:
+        """
+        partial
+        """
+        return _God.spy(iterable, lambda v, _: predicate(v) and None, _God.Default.true)
+
+    @staticmethod
+    def all_isinstance(iterable: Iterable[T], *types: OptionalType) -> bool:
+        """
+        partial
+        """
+        types = _God.help_make_set(types)
+        return ListOperations.all(iterable, lambda v: type(v) in types)
+
+    @staticmethod
+    def any(iterable: Iterable[T], predicate: ElementPredicate[T]) -> bool:
+        """
+        partial
+        """
+        return _God.spy(iterable, lambda v, _: predicate(v) or None, _God.Default.false)
+
+    @staticmethod
+    def indices(iterable: Iterable[T]) -> Iterable[int]:
+        """
+        partial
+        """
+        return _God.new(iterable, lambda _, i: i)
+
+    @staticmethod
+    def take(iterable: Iterable[T], predicate: ElementPredicate[T]) -> Iterable[T]:
+        """
+        complete
+        """
+        return _God.new(iterable, lambda v, _: _God.yield_(v) if predicate(v) else None)
+
+    @staticmethod
+    def transform(
+        iterable: Iterable[T], *transformers: OptionalElementTransformer
+    ) -> Iterable:
+        """
+        complete
+        """
+
+        def _transform_element(element, _):
+            for transformer in transformers:
+                if transformer is not None:
+                    element = transformer(element)
+            return element
+
+        return _God.new(iterable, _transform_element)
+
+    @staticmethod
+    def take_n(iterable: Iterable[T], n: int) -> Iterable[T]:
+        """
+        partial
+        """
+        if n < 0:
+            return iterable
+        elif n == 0:
+            return []
+        return range(n)._god_yield(
+            iterable, lambda v, i: _yield(v) if i < n else _return()
+        )
+
+    @staticmethod
+    def take_by_indices(iterable: Iterable[T], *indices: OptionalIndex) -> Iterable[T]:
+        """
+        partial
+        """
+        indices = set(indices) - {None}
+        max_index = max(indices)
+        iterable = ListOperations.take_n(iterable, max_index + 1)
+        return _god_yield(iterable, lambda v, i: _yield(v) if i in indices else None)
+
+    @staticmethod
+    def first(iterable: Iterable[T]) -> T | CRU_NOT_FOUND:
+        """
+        partial
+        """
+        result_iterable = ListOperations.take_n(iterable, 1)
+        for element in result_iterable:
+            return element
+        return CRU_NOT_FOUND
+
+    @staticmethod
+    def first_index(
+        iterable: Iterable[T], predicate: ElementPredicate[T]
+    ) -> int | CRU_NOT_FOUND:
+        """
+        partial
+        """
+        for index, element in enumerate(iterable):
+            if predicate(element):
+                return index
+
+    @staticmethod
+    def take_indices(
+        iterable: Iterable[T], predicate: ElementPredicate[T]
+    ) -> Iterable[int]:
+        """
+        complete
+        """
+        for index, element in enumerate(iterable):
+            if predicate(element):
+                yield index
+
+    @staticmethod
+    def _flatten(o, depth: int, max_depth: int) -> Iterable:
+        if depth == max_depth or not isinstance(o, Iterable):
+            yield o
+            return
+        for v in o:
+            yield from ListOperations._flatten(v, depth + 1, max_depth)
+
+    @staticmethod
+    def flatten(o, max_depth=-1) -> Iterable:
+        """
+        complete
+        """
+        return ListOperations._flatten(o, 0, max_depth)
+
+    @staticmethod
+    def skip_by_indices(iterable: Iterable[T], *indices: OptionalIndex) -> Iterable[T]:
+        """
+        complete
+        """
+        indices = set(indices) - {None}
+        for index, element in enumerate(iterable):
+            if index not in indices:
+                yield element
+
+    @staticmethod
+    def skip_if(iterable: Iterable[T], predicate: ElementPredicate[T]) -> list[T]:
+        """
+        complete
+        """
+        for element in iterable:
+            if not predicate(element):
+                yield element
+
+    @staticmethod
+    def remove_all_if(l: Iterable[T], p: ElementPredicate[T]) -> list[T]:
+        return [v for v in l if not p(v)]
+
+    @staticmethod
+    def remove_all_value(l: Iterable[T], *r: Any) -> list[T]:
+        return [v for v in l if v not in r]
+
+    @staticmethod
+    def replace_all_value(l: Iterable[T], old_value: Any, new_value: R) -> list[T | R]:
+        return [new_value if v == old_value else v for v in l]
+
+    @staticmethod
+    def foreach(iterable: Iterable[T], *f: OptionalElementOperation[T]) -> None:
+        if len(f) == 0:
+            return
+        for v in iterable:
+            for f_ in f:
+                if f_ is not None:
+                    f_(v)
+
+    @staticmethod
+    def make(v: CanBeList[T], /, none_to_empty_list: bool = True) -> list[T]:
+        if v is None and none_to_empty_list:
+            return []
+        return list(v) if isinstance(v, Iterable) else [v]
+
+
+class CruList(list, Generic[T]):
+    @property
+    def is_empty(self) -> bool:
+        return len(self) == 0
+
+    def sub_by_indices(self, *index: int) -> "CruList"[T]:
+        return CruList(ListOperations.sub_by_indices(self, *index))
+
+    def split_by_indices(self, *index: int) -> tuple["CruList"[T], "CruList"[T]]:
+        l1, l2 = ListOperations.split_by_indices(self, *index)
+        return CruList(l1), CruList(l2)
+
+    def complement_indices(self, *index: int) -> list[int]:
+        return ListOperations.complement_indices(len(self), *index)
+
+    def foreach(self, *f: OptionalElementOperation[T]) -> None:
+        ListOperations.foreach(self, *f)
+
+    def all(self, p: ElementPredicate[T]) -> bool:
+        return ListOperations.all(self, p)
+
+    def all_is_instance(self, *t: type) -> bool:
+        return ListOperations.all_isinstance(self, *t)
+
+    def any(self, p: ElementPredicate[T]) -> bool:
+        return ListOperations.any(self, p)
+
+    def find_all_if(self, p: ElementPredicate[T]) -> "CruList"[T]:
+        return CruList(ListOperations.take(self, p))
+
+    def find_if(self, p: ElementPredicate[T]) -> T | CRU_NOT_FOUND:
+        return ListOperations.first(self, p)
+
+    def find_all_indices_if(self, p: ElementPredicate[T]) -> "CruList"[int]:
+        return CruList(ListOperations.take_indices(self, p))
+
+    def find_index_if(self, p: ElementPredicate[T]) -> int | CRU_NOT_FOUND:
+        return ListOperations.first_index(self, p)
+
+    def split_if(self, p: ElementPredicate[T]) -> tuple["CruList"[T], "CruList"[T]]:
+        l1, l2 = ListOperations.split_if(self, p)
+        return CruList(l1), CruList(l2)
+
+    def split_by_types(self, *t: type) -> tuple["CruList"[T], "CruList"[T]]:
+        l1, l2 = ListOperations.split_by_types(self, *t)
+        return CruList(l1), CruList(l2)
+
+    def transform(self, *f: OptionalElementTransformer) -> "CruList"[Any]:
+        return CruList(ListOperations.transform(self, *f))
+
+    def transform_if(
+        self, f: OptionalElementTransformer, p: ElementPredicate[T]
+    ) -> "CruList"[Any]:
+        return CruList(ListOperations.transform_if(self, f, p))
+
+    def remove_by_indices(self, *index: int) -> "CruList"[T]:
+        return CruList(ListOperations.skip_by_indices(self, *index))
+
+    def remove_if(self, p: ElementPredicate[T]) -> "CruList"[T]:
+        return CruList(ListOperations.remove_if(self, p))
+
+    def remove_all_if(self, p: ElementPredicate[T]) -> "CruList"[T]:
+        return CruList(ListOperations.remove_all_if(self, p))
+
+    def remove_all_value(self, *r: Any) -> "CruList"[T]:
+        return CruList(ListOperations.remove_all_value(self, *r))
+
+    def replace_all_value(self, old_value: Any, new_value: R) -> "CruList"[T | R]:
+        return CruList(ListOperations.replace_all_value(self, old_value, new_value))
+
+    @staticmethod
+    def make(l: CanBeList[T]) -> "CruList"[T]:
+        return CruList(ListOperations.make(l))
+
+
+class CruInplaceList(CruList, Generic[T]):
+
+    def clear(self) -> "CruInplaceList[T]":
+        self.clear()
+        return self
+
+    def extend(self, *l: Iterable[T]) -> "CruInplaceList[T]":
+        self.extend(l)
+        return self
+
+    def reset(self, *l: Iterable[T]) -> "CruInplaceList[T]":
+        self.clear()
+        self.extend(l)
+        return self
+
+    def transform(self, *f: OptionalElementTransformer) -> "CruInplaceList"[Any]:
+        return self.reset(super().transform(*f))
+
+    def transform_if(
+        self, f: OptionalElementTransformer, p: ElementPredicate[T]
+    ) -> "CruInplaceList"[Any]:
+        return self.reset(super().transform_if(f, p))
+
+    def remove_by_indices(self, *index: int) -> "CruInplaceList"[T]:
+        return self.reset(super().remove_by_indices(*index))
+
+    def remove_all_if(self, p: ElementPredicate[T]) -> "CruInplaceList"[T]:
+        return self.reset(super().remove_all_if(p))
+
+    def remove_all_value(self, *r: Any) -> "CruInplaceList"[T]:
+        return self.reset(super().remove_all_value(*r))
+
+    def replace_all_value(
+        self, old_value: Any, new_value: R
+    ) -> "CruInplaceList"[T | R]:
+        return self.reset(super().replace_all_value(old_value, new_value))
+
+    @staticmethod
+    def make(l: CanBeList[T]) -> "CruInplaceList"[T]:
+        return CruInplaceList(ListOperations.make(l))
+
+
+K = TypeVar("K")
+
+
+class CruUniqueKeyInplaceList(Generic[T, K]):
+    KeyGetter = Callable[[T], K]
+
+    def __init__(
+        self, get_key: KeyGetter, *, before_add: Callable[[T], T] | None = None
+    ):
+        super().__init__()
+        self._get_key = get_key
+        self._before_add = before_add
+        self._l: CruInplaceList[T] = CruInplaceList()
+
+    @property
+    def object_key_getter(self) -> KeyGetter:
+        return self._get_key
+
+    @property
+    def internal_list(self) -> CruInplaceList[T]:
+        return self._l
+
+    def validate_self(self):
+        keys = self._l.transform(self._get_key)
+        if len(keys) != len(set(keys)):
+            raise ValueError("Duplicate keys!")
+
+    def get_or(self, k: K, fallback: Any = CRU_NOT_FOUND) -> T | Any:
+        r = self._l.find_if(lambda i: k == self._get_key(i))
+        return r if r is not CRU_NOT_FOUND else fallback
+
+    def get(self, k: K) -> T:
+        v = self.get_or(k, CRU_NOT_FOUND)
+        if v is CRU_NOT_FOUND:
+            raise KeyError(f"Key not found!")
+        return v
+
+    def has_key(self, k: K) -> bool:
+        return self.get_or(k, CRU_NOT_FOUND) is not CRU_NOT_FOUND
+
+    def has_any_key(self, *k: K) -> bool:
+        return self._l.any(lambda i: self._get_key(i) in k)
+
+    def try_remove(self, k: K) -> bool:
+        i = self._l.find_index_if(lambda v: k == self._get_key(v))
+        if i is CRU_NOT_FOUND:
+            return False
+        self._l.remove_by_indices(i)
+        return True
+
+    def remove(self, k: K, allow_absense: bool = False) -> None:
+        if not self.try_remove(k) and not allow_absense:
+            raise KeyError(f"Key {k} not found!")
+
+    def add(self, v: T, /, replace: bool = False) -> None:
+        if self.has_key(self._get_key(v)):
+            if replace:
+                self.remove(self._get_key(v))
+            else:
+                raise ValueError(f"Key {self._get_key(v)} already exists!")
+        if self._before_add is not None:
+            v = self._before_add(v)
+        self._l.append(v)
+
+    def set(self, v: T) -> None:
+        self.add(v, True)
+
+    def extend(self, l: Iterable[T], /, replace: bool = False) -> None:
+        if not replace and self.has_any_key([self._get_key(i) for i in l]):
+            raise ValueError("Keys already exists!")
+        if self._before_add is not None:
+            l = [self._before_add(i) for i in l]
+        keys = [self._get_key(i) for i in l]
+        self._l.remove_all_if(lambda i: self._get_key(i) in keys).extend(l)
+
+    def clear(self) -> None:
+        self._l.clear()
+
+    def __iter__(self):
+        return iter(self._l)
+
+    def __len__(self):
+        return len(self._l)
diff --git a/tools/cru-py/cru/_util/_type.py b/tools/cru-py/cru/_util/_type.py
new file mode 100644
index 0000000..dc50def
--- /dev/null
+++ b/tools/cru-py/cru/_util/_type.py
@@ -0,0 +1,42 @@
+from types import NoneType
+from typing import Any
+
+from ._list import CanBeList, CruList
+
+DEFAULT_NONE_ERR = ValueError
+DEFAULT_NONE_ERR_MSG = "None is not allowed here."
+DEFAULT_TYPE_ERR = ValueError
+DEFAULT_TYPE_ERR_MSG = "Type of object is not allowed here."
+
+
+class TypeSet(set[type]):
+    def __init__(self, *l: type):
+        l = CruList.make(l).remove_all_value(None, NoneType)
+        if not l.all_is_instance(type):
+            raise TypeError("t must be a type or None.")
+        super().__init__(l)
+
+    def check_value(self, v: Any, /, allow_none: bool, empty_allow_all: bool = True, *,
+                    none_err: type[Exception] = DEFAULT_NONE_ERR,
+                    none_err_msg: str = DEFAULT_NONE_ERR_MSG,
+                    type_err: type[Exception] = DEFAULT_TYPE_ERR,
+                    type_err_msg: str = DEFAULT_TYPE_ERR_MSG) -> None:
+        if v is None:
+            if allow_none:
+                return
+            else:
+                raise none_err(none_err_msg)
+        if len(self) == 0 and empty_allow_all:
+            return
+        if type(v) not in self:
+            raise type_err(type_err_msg)
+
+    def check_value_list(self, l: CanBeList, /, allow_none: bool, empty_allow_all: bool = True, *,
+                         none_err: type[Exception] = DEFAULT_NONE_ERR,
+                         none_err_msg: str = DEFAULT_NONE_ERR_MSG,
+                         type_err: type[Exception] = DEFAULT_TYPE_ERR,
+                         type_err_msg: str = DEFAULT_TYPE_ERR_MSG) -> None:
+        l = CruList.make(l)
+        for v in l:
+            self.check_value(v, allow_none, empty_allow_all, none_err=none_err, none_err_msg=none_err_msg,
+                             type_err=type_err, type_err_msg=type_err_msg)