708 

   708 

   709     def __eq__(self, other):

   709     def __eq__(self, other):

   710         if hasattr(other, 'expression'):

   710         if hasattr(other, 'expression'):

   711             return self.expression == other.expression

   711             return self.expression == other.expression

   712         return False

   712         return False

   713 

   716 

   714     def __deepcopy__(self, memo):

   717     def __deepcopy__(self, memo):

   715         return self.__class__(self.expression, self.mainvars)

   718         return self.__class__(self.expression, self.mainvars)

   716     def __getstate__(self):

   719     def __getstate__(self):

   717         return (self.expression, self.mainvars)

   720         return (self.expression, self.mainvars)