code: function getKey() {
        let paramString =
          width + 'x' + height + '-'
          + path
          + (is2x ? '-@2x' : '')
          + (bg ? `_${bg}` : '')
          + (crop ? '_crop' : '')
          + (mode ? `_${mode}` : '')
          + (trim ? '_trim' : '');
  
        return paramString + '-' + crypto.createHash('sha1').update(paramString).digest('hex');
      }
docs: Builds a cache key for the adapted image
  
  @returns {string}