code: def dataframe(start_row=0, max_rows=None, use_cache=True):
      
      output = QueryOutput()
      output._output_type = 'dataframe'
      output._dataframe_start_row = start_row
      output._dataframe_max_rows = max_rows
      output._use_cache = use_cache
      return output
docs: Construct a query output object where the result is a dataframe
  
      Args:
        start_row: the row of the table at which to start the export (default 0).
        max_rows: an upper limit on the number of rows to export (default None).
        use_cache: whether to use cached results or not (default True).