code: function EE(fn, context, once) {
    this.fn = fn;
    this.context = context;
    this.once = once || false;
  }
docs: Representation of a single event listener.
  
  @param {Function} fn The listener function.
  @param {*} context The context to invoke the listener with.
  @param {boolean} [once=false] Specify if the listener is a one-time listener.
  @constructor
  @private