    def extract
      Google::Apis::RequestOptions.default.retries = @retries
      service                                      = Google::Apis::SheetsV4::SheetsService.new
      service.client_options.application_name      = @application_name
      service.authorization                        = authorize()
      @data                                        = []

      entries.each do |file|
        logger.info "Extracting Google Sheet data from #{file.pathname}, with sheet name : #{@sheet_name}"
        response = get_spreadsheet_vals(service, file.raw, @sheet_name)
        data.push(response)
      end

      self
    end