code: function toHexString(arr) {
                  var str = '';
                  for (var i = 0; i < arr.length; i++) {
                      var obj = (arr[i] >>> 0).toString(16);
                      str += '00000000'.substr(obj.length) + obj;
                  }
                  return str;
              }
docs: Translates an array of numbers to a hex string
  @param {Array} arr
  @returns {string}