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__