code: function handleProxyEvent(source, target, eventName, options) {
      let {newEventName, prependSourceArg} = options || {};
  
      source.on(eventName, function (...args) {
          prependSourceArg && args.unshift(source);
  
          if (typeof newEventName === 'function') {
              newEventName.apply(target, args);
          }
          else {
              newEventName || (newEventName = eventName);
              args.unshift(newEventName);
              target.emit.apply(target, args);
          }
      });
  }
docs: Handle the event proxy
  
  @inner
  @param {EventEmitter} source the event trigger source
  @param {EventEmitter} target the proxy target
  @param {string} eventName the proxy event name
  @param {Object=} options the proxy options
  @param {string|Function=} options.newEventName the new event name to trigger
  or default event handler
  @param {boolean=} options.prependSourceArg whether prepend the original event
  trigger to event handler argument list. By default, false.