Maybe Monad in Python 3

maybe_monad.py

#!/usr/bin/env python3
from typing import TypeVar, Generic, NoReturn, Callable
import functools

T = TypeVar('T')


class Maybe(Generic[T]):
    def __init__(self, value: T) -> None:
        self.value = value

    def __repr__(self) -> str:
        return(f"Maybe({self.value})")

    def get(self) -> T:
        return self.value


def with_maybe(transform: Callable[[T], T]) -> Callable:
    @functools.wraps(transform)
    def wrapper(input_: Maybe[T]) -> Maybe[T]:
        if input_.value is None:
            return Maybe(None)
        return Maybe(transform(input_.value))
    return wrapper


@with_maybe
def add_one(x: int) -> int:
    return x + 1


@with_maybe
def multiply_by_two(x: int) -> int:
    return x * 2


n0: str = input("Please enter an integer: ")
print(f"n0 = '{n0}'")
n1: Maybe[int] = Maybe(None if n0 == "" else int(n0))
print(f"n1 = {n1}")
n2: Maybe[int] = add_one(n1)
print(f"n2 = {n2}")
n3: Maybe[int] = multiply_by_two(n2)
print(n3.value)