maybe.py

class Just:
    def __init__(self, value):
        self.value = value

    def __repr__(self):
        return f'Just({self.value.__repr__()})'

    def __eq__(self, other):
        if isinstance(other, Just):
            return self.value == other.value
        return False

    def map(self, f):
        if self.value is None:
            return Nothing()
        if f(self.value) is None:
            return Nothing()
        return Just(f(self.value))


class Nothing:
    def __repr__(self):
        return 'Nothing'

    def __eq__(self, other):
        if isinstance(other, Nothing):
            return True
        return False

    def map(self, f):
        return self