/**
 * Generates a correctly formatted GUID
 */
function guid () {

  var guid = 'xxxxxxxx-xxxx-xxxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, (c) => {

    var r = Math.random() * 16 | 0;
    var v = c === 'x' ? r : (r & 0x3 | 0x8);

    return v.toString(16);

  });

  return guid;
};