docs: function doRegister( event, responsible ) {
      var hammerEvent = getEventNameForPrefix( event, "hammer." );
      if ( hammerEvent && !this._hammer ) {
          this._hammer = new Hammer( this.$, { domEvents: true } );
          // To get domEvents.stopPropagation() available.
          this._hammer.domEvents = true;
      }
  
      var eventDef = this._events[ event ];
      if ( !eventDef ) {
          var handler = handlerWithChainOfResponsability.bind( this, event );
          eventDef = { chain: [], handler: handler };
          if ( hammerEvent ) this._hammer.on( hammerEvent, handler );
          else this.$.addEventListener( event, handler );
          this._events[ event ] = eventDef;
      }
      eventDef.chain.push( responsible );
  }