function syncRepeat() {
    /*
    Gets all of the repeat classes
    */
    var repeatClasses = document.getElementsByClassName("amplitude-repeat");

    /*
    Iterate over all of the repeat classes. If repeat is on,
    then add the 'amplitude-repeat-on' class and remove the
    'amplitude-repeat-off' class. If it's off, then do the
    opposite.
    */
    for (var i = 0; i < repeatClasses.length; i++) {
      if (_config2.default.repeat) {
        repeatClasses[i].classList.add("amplitude-repeat-on");
        repeatClasses[i].classList.remove("amplitude-repeat-off");
      } else {
        repeatClasses[i].classList.remove("amplitude-repeat-on");
        repeatClasses[i].classList.add("amplitude-repeat-off");
      }
    }
  }
Syncs repeat for all of the repeat buttons. Users
can apply styles to the 'amplitude-repeat-on' and
'amplitude-repeat-off' classes. They represent the state
of the player.