function EventPatternObservable(add, del, fn) {
      this._add = add;
      this._del = del;
      this._fn = fn;
      __super__.call(this);
    }
Creates an observable sequence by adding an event listener to the matching DOMElement or each item in the NodeList.
@param {Object} element The DOMElement or NodeList to attach a listener.
@param {String} eventName The event name to attach the observable sequence.
@param {Function} [selector] A selector which takes the arguments from the event handler to produce a single item to yield on next.
@returns {Observable} An observable sequence of events from the specified element and the specified event.