pytype.py

from typing import Callable
from typing import TypeVar

A = TypeVar('A')
B = TypeVar('B')

def apply(f: Callable[[A],B], a: A):
    return f(a)

def fst(a: A, b: B):
    return a

def a(n):
    return n
  
apply(a, 10)
fst(10, "str")  
 

  
  
from typing import Union

def Add(a: Union[str, int], b: Union[str, int]) -> Union[str, int]:
        return a + b