(self)
return False
Override Function's is_commutative so that order is preserved in
        represented expressions
Override Function's is_commutative so that order is preserved in
        represented expressions
Override Function s is_commutative so that order is preserved in represented expressions
def is_commutative(self):
        """
        Override Function's is_commutative so that order is preserved in
        represented expressions
        """
        return False
def is_commutative ( self ) : return False