def st_require_cols dict
      dcols = dict.keys.to_set
      unless @require_cols.subset? dict.keys.to_set
        missing_cols = (@require_cols - dcols).to_a
        raise ReindeerETL::Errors::RecordInvalid.new("Missing required columns: #{missing_cols}")
      end
    end
def st_require_cols dict
      dcols = dict.keys.to_set
      unless @require_cols.subset? dict.keys.to_set
        missing_cols = (@require_cols - dcols).to_a
        raise ReindeerETL::Errors::RecordInvalid.new("Missing required columns: #{missing_cols}")
      end
    end
require these columns