I have a python script and trying to add type hints to the code, Following is the sample code (without type hints the code works) using mypy.

values_int: list[int] = [1, 2, 3, 4]
values_str: list[str] = ["1", "2", "3", "4"]

def bar(*, x: list[int]) -> bool:
    # processing
    return True

def baz(*, y: list[str]) -> bool:
    # processing
    return True

def foo(*, values: list[int] | list[str]) -> bool:
    status: bool = False

    if isinstance(values[0], int):
        x: list[int] = values
        status = bar(x=x)

    elif isinstance(values[0], str):
        # case-1
        # status = baz(y=values)

        # case-2
        y: list[str] = values
        status = baz(y=y)

    return status

foo(values=values_str)

Errors for:

# case-1
#  error: Argument "y" to "baz" has incompatible type "list[int] | list[str]"; expected "list[str]"

# case-2
#  error: Incompatible types in assignment (expression has type "list[int] | list[str]", variable has type "list[str]")