code: function () {
          var contentEncoding = this.headers.get(CONTENT_ENCODING),
              body = this.stream || this.body,
              source;
  
          if (contentEncoding) {
              source = HEADER;
          }
  
          // if the encoding is not found, we check
          else if (body) { // @todo add detection for deflate
              // eslint-disable-next-line lodash/prefer-matches
              if (body[0] === 0x1F && body[1] === 0x8B && body[2] === 0x8) {
                  contentEncoding = GZIP;
              }
  
              if (contentEncoding) {
                  source = BODY;
              }
          }
  
          return {
              format: contentEncoding,
              source: source
          };
      }
docs: Returns the response encoding defined as header or detected from body.
  
  @private
  @returns {Object} - {format: string, source: string}