code: function bind(element, eventName, callback) {
    element.addEventListener(eventName, callback);
  
    return function unbind() {
      element.removeEventListener(eventName, callback);
    };
  }
docs: bind - listens to event on element, returning a function to stop listening to the event.
  @param {EventTarget} element - https://developer.mozilla.org/en-US/docs/Web/API/EventTarget
  @param {String} eventName - Name of the event. Like 'click', or 'did-custom-event'
  @param {Function} callback -
  @return unbind - function that unbinds the callback from the event on element.