Redefinitions with incompatible types

Each name within a function only has a single ‘declared’ type. You canreuse for loop indices etc., but if you want to use a variable withmultiple types within a single function, you may need to declare itwith the Any type.

def f() -> None:
    n = 1
    ...
    n = 'x'        # Type error: n has type int

Note

This limitation could be lifted in a future mypyrelease.

Note that you can redefine a variable with a more precise or a moreconcrete type. For example, you can redefine a sequence (which doesnot support sort()) as a list and sort it in-place:

def f(x: Sequence[int]) -> None:
    # Type of x is Sequence[int] here; we don't know the concrete type.
    x = list(x)
    # Type of x is List[int] here.
    x.sort()  # Okay!