二元运算符 特殊方法 + __add__,__radd__ - __sub__,__rsub__ * __mul__,__rmul__ / __div__,__rdiv__,__truediv__,__rtruediv__ // __floordiv__,__rfloordiv__ % __mod__,__rmod__ ** __pow__,__rpow__ << __lshift__,__rlshift__ >> __rshift__,__rrshift__ & __and__,__rand__ ^ __xor__,__rxor__ | __or__,__ror__ += __iaddr__ -= __isub__ *= __imul__ /= __idiv__,__itruediv__ //= __ifloordiv__ %= __imod__ **= __ipow__ <<= __ilshift__ >>= __irshift__ &= __iand__ ^= __ixor__ |= __ior__ == __eq__ !=,<> __ne__ > __get__ < __lt__ >= __ge__ <= __le__