class_docstr: Sqlite backed document storage.
  
  Implements get_doc_text(doc_id).
docstr: Close the connection to the database.
code: def close(self):
      """
      Close the connection to the database.
      """
      self.connection.close()
  
file_path: ParlAI/parlai/agents/tfidf_retriever/doc_db.py
imports: import sqlite3
  from .None import utils
label_desc: Use image node_id 4 for calling the DocDB obj's underlying member method code with example usage: obj.close() without return types