code: def create_index(self, table_name, attr_name):
          
  
          self.verify_table_existence(table_name)
          self.validate_access_permission(["w", "a"])
  
          query_format = "CREATE INDEX IF NOT EXISTS {index:s} ON {table}({attr})"
          query = query_format.format(
              index=make_index_name(table_name, attr_name),
              table=Table(table_name),
              attr=Attr(attr_name),
          )
  
          logger.debug(query)
          self.execute_query(query, logging.getLogger().findCaller())
docs: :param str table_name:
              Table name that contains the attribute to be indexed.
          :param str attr_name: Attribute name to create index.
          :raises IOError: |raises_write_permission|
          :raises simplesqlite.NullDatabaseConnectionError:
              |raises_check_connection|
          :raises simplesqlite.TableNotFoundError:
              |raises_verify_table_existence|