How to indicate a callable is of a certain type?

For example, we can indicate a variable is of a certain type:

a: float = 5.

Can we also indicate that a function is of a certain type?

import typing

FunctionType = typing.Callable[[float],float]

def a(v: float)->float:
    return v

How do we specify that we intend 'a' to be of type 'FunctionType'?