code: function QueryString (qs) {
          var parts = qs.split('&');
  
          for (var i = 0, s = parts.length; i < s; i++) {
              var keyVal = parts[i].split('=');
              var key = decodeURIComponent(keyVal[0].replace(RX_PLUS, ' '));
  
              if (!key) {
                  continue;
              }
  
              var value = keyVal[1] !== undefined ? decode(keyVal[1]) : null;
  
              if (typeof this[key] === 'undefined') {
                  this[key] = value;
              } else {
                  if (!(this[key] instanceof Array)) {
                      this[key] = [this[key]];
                  }
  
                  this[key].push(value);
              }
          }
      }
docs: Class QueryString
  
  @param {string} qs - string representation of QueryString
  @constructor