code: def check_for_errors(response)
        # Check for error code.
        if response.code != 200
          # Check for error in body.
          report_body = response.body
          check_for_xml_error(report_body, response.code)
          # No XML error found nor raised, falling back to a default message.
          raise AdwordsApi::Errors::ReportError.new(response.code,
              'HTTP code: %d, body: %s' % [response.code, response.body])
        end
        return nil
      end
docs: Checks downloaded data for error signature. Raises ReportError if it
   detects an error.