code: def query_uast(self, query, query_col='uast', output_col='result'):
          
          return UASTsDataFrame(self._engine_dataframe.queryUAST(query,
                                         query_col,
                                         output_col),
                                self._session, self._implicits)
docs: Queries the UAST of a file with the given query to get specific nodes.
  
          >>> rows = uasts_df.query_uast('//*[@roleIdentifier]').collect()
          >>> rows = uasts_df.query_uast('//*[@roleIdentifier]', 'foo', 'bar')
  
          :param query: xpath query
          :type query: str
          :param query_col: column containing the list of nodes to query
          :type query_col: str
          :param output_col: column to place the result of the query
          :type output_col: str
          :rtype: UASTsDataFrame