code: def test_drop_kb(self):
      # create a knowledge base
      sql = f"""
              CREATE KNOWLEDGE BASE test_kb
              USING
              MODEL = {self.embedding_model_name},
              STORAGE = {self.vector_database_name}.{self.vector_database_table_name}
          """
      self.run_sql(sql)
  
      # verify the knowledge base is created
      kb_obj = (
          self.db.session.query(KnowledgeBase)
          .filter_by(name="test_kb")
          .first()
      )
      assert kb_obj is not None
  
      # drop a knowledge base
      sql = """
              DROP KNOWLEDGE BASE test_kb
          """
      self.run_sql(sql)
  
      # verify the knowledge base is dropped
      kb_obj = (
          self.db.session.query(KnowledgeBase)
          .filter_by(name="test_kb")
          .first()
      )
      assert kb_obj is None
  
imports: import tempfile
  import time
  from unittest.mock import patch
  import pandas
  import pytest
  from mindsdb_sql import parse_sql
  from mindsdb.interfaces.storage.db import KnowledgeBase
  from .executor_test_base import BaseExecutorTest
label_desc: Use image node_id 6 for calling the TestKnowledgeBase obj's underlying member method code with example usage: obj.test_drop_kb() without return types