code: function(event) {
          var data, extraArgs, key, transitions = this._transitions
          if (transitions.hasOwnProperty((key = this.currentState)) &&
            transitions[key].hasOwnProperty(event)) {
            data = transitions[key][event]
          } else if (transitions.hasOwnProperty(ANY_STATE) &&
            transitions[ANY_STATE].hasOwnProperty(event)) {
            data = transitions[ANY_STATE][event]
          } else return
  
          extraArgs = _.toArray(arguments).slice(1)
          this._doTransition.apply(this, [data, event].concat(extraArgs))
        }
docs: Callback bound to all events. If no transition available, do nothing. Otherwise, starts the transition.