docs: function exitConcurrent(opts) {
      var root = this.root(), i, n;
  
      for (i = 0, n = this.substates.length; i < n; i++) {
        exit.call(this.substates[i], opts);
      }
  
      callExitHandlers.call(this, opts.context);
      this.__isCurrent__ = false;
      if (this !== root) { trace.call(this, "State: [EXIT]   : " + this.path()); }
  
      return this;
    }