code: def insert(self, document):
          
  
          doc_id = self._get_doc_id(document)
          data = self._read()
          data[doc_id] = dict(document)
          self._write(data)
  
          return doc_id
docs: Insert a new document into the table.
  
          :param document: the document to insert
          :returns: the inserted document's ID