function querystring(query) {
  var parser = /([^=?&]+)=?([^&]*)/g
    , result = {}
    , part;

  while (part = parser.exec(query)) {
    var key = decode(part[1])
      , value = decode(part[2]);

    //
    // Prevent overriding of existing properties. This ensures that build-in
    // methods like `toString` or __proto__ are not overriden by malicious
    // querystrings.
    //
    // In the case if failed decoding, we want to omit the key/value pairs
    // from the result.
    //
    if (key === null || value === null || key in result) continue;
    result[key] = value;
  }

  return result;
}
Simple query string parser.

@param {String} query The query string that needs to be parsed.
@returns {Object}
@api public