code: function (gesture, lastGesture) {
      if (gesture) {
        this.playAnimation(gesture || ANIMATIONS.open, lastGesture, false);
        return;
      }
  
      // If no gesture, then reverse the current gesture back to open pose.
      this.playAnimation(lastGesture, lastGesture, true);
    }
docs: Play gesture animation.
  
  @param {string} gesture - Which pose to animate to. If absent, then animate to open.
  @param {string} lastGesture - Previous gesture, to reverse back to open if needed.