code: function toColorHexString(ref) {
      var results = [];
  
      for (var j = 0, len = ref.length; j < len; j++) {
          results.push(toHexString(ref[j]));
      }
  
      return '#' + results.join('');
  }
docs: Converts from an array of numbers like [15, 15, 15] to a hex string like 'FFF'
  @param {[red, green, blue]} ref
  @returns {string}