return_not_implemented.py

class RealNumber:
    """Represents a real number."""

    def __init__(self, val):
        self.val = val

    def __add__(self, other):
        return NotImplemented


class ComplexNumber:
    """Represents an imaginary number."""

    def __init__(self, x, y):
        self.x = x
        self.y = y

    def __add__(self, other):
        return self.val + other.val

    def __radd__(self, other):
        res = (self.x + other.val, self.y)
        return res


if __name__ == "__main__":
    complex_num = ComplexNumber(2, 5)
    real_num = RealNumber(32)