code: function initSkeleton(scene) {
  	return new Promise((resolve, reject) => {
  		let skel = null;
  
  		// Attempt to use existing skeleton when available
  		scene.traverse(child => {
  			if(child.type === 'TrackingSkeleton') {
  				skel = child;
  				return;
  			}
  		});
  
  		if(skel)
  			return resolve(skel);
  
  		// Skeleton has not been assigned to scene yet
  		altspace.getThreeJSTrackingSkeleton().then(function(trackingSkeleton) {
  			skel = trackingSkeleton;
  			scene.add(skel);
  			return resolve(skel);
  		});
  	});
  }
docs: An array in the form of `[bodyPart, side, subIndex]` identifying a joint in the tracking skeleton.
  E.g. `['Index', 'Left', 0]` identifies the first joint on the index finger of the left hand.
  See [TrackingSkeleton#getJoint]{@link module:altspace~TrackingSkeleton#getJoint} for available
  joint names.
  @typedef {Array.<String, String, Number>} module:altspace/utilities/behaviors.JointCollisionEvents~JointId
   helper function to guarantee skeleton presence, and fetch if available