docs: function (targetScope, key) {
              var target;
              if (this.$targets) {
                  for (var i = 0; i < this.$targets.length; i++) {
                      target = this.$targets[i];
                      if (target.key === key && target.scope === targetScope) {
                          this.$targets.splice(i, 1);
                          break;
                      }
                  }
                  if (this.$targets.length === 0) {
                      this.destroy();
                  }
              }
          }