Functionality to copy and enforce signatures of function declarations

[KotlinIsland]

def foo(a: int) -> str: ...

@func_type[foo]
def bar():  # missing parameter 'a'
    return 1   # expected return str, found int
    
# OR
def bar(*args: ParamSpec[foo].args, **kwargs: ParamSpec[foo].kwargs) -> ???[foo].return:
    return foo(*args, **kwargs)

A member on the design team had this to say:

class Callable[**P, R]:
    type args = P.args
    type kwargs:= P.kwargs
    type return_type = R
    
def bar(*args: foo.args, **kwargs: foo.kwargs) -> foo.return_type: ...
# and a runtime version like:
def bar(*args: Callable[foo].args, **kwargs: Callable[foo].kwargs) -> Callable[foo].return_type: ...