class Commuter1:
    def __init__(self, val):
        self.val = val

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

    def __radd__(self, other):
        print('radd', self.val, other)
        return other + self.val


class Commuter2:
    def __init__(self, val):
        self.val = val

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

    def __radd__(self, other):
        return self.__add__(other)              # Call __add__ explicitly

class Commuter3:
    def __init__(self, val):
        self.val = val

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

    def __radd__(self, other):
        return self + other                     # Swap order and re-add

class Commuter4:
    def __init__(self, val):
        self.val = val

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

    __radd__ = __add__                          # Alias: cut out the middleperson


class Commuter5:                                # Propagate class type in results
    def __init__(self, val):
        self.val = val

    def __add__(self, other):
        if isinstance(other, Commuter5):        # Type test to avoid object nesting
            other = other.val
        return Commuter5(self.val + other)      # Else + result is another Commuter

    def __radd__(self, other):
        return Commuter5(other + self.val)

    def __repr__(self):
        return f'Commuter5({self.val})'

class Commuter6:                                # Propagate class type in results
    def __init__(self, val):
        if isinstance(val, Commuter6):          # Type test to avoid object nesting
            self.val = val.val
        else:
            self.val = val

    def __add__(self, other):
        return Commuter6(self.val + other)

    def __radd__(self, other):
        return Commuter6(other + self.val)

    def __repr__(self):
        return f'Commuter6({self.val})'


if __name__ == '__main__':
    for klass in (Commuter1, Commuter2, Commuter3, Commuter4, Commuter5, Commuter6):
        print('-' * 50)
        x = klass(88)
        y = klass(99)
        print(x + 1)
        print(1 + y)
        print(x + y)