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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def delete_user(self, user, group):
 """ Deletes user from group """

        if not self.__contains__(group):
            raise GroupNotExists
        if not self.is_user_in(user, group):
            raise UserNotInAGroup
        self.new_groups.popvalue(group, user)