code: function ( layersMap ) {
  
  			var rawStacks = fbxTree.Objects.AnimationStack;
  
  			// connect the stacks (clips) up to the layers
  			var rawClips = {};
  
  			for ( var nodeID in rawStacks ) {
  
  				var children = connections.get( parseInt( nodeID ) ).children;
  
  				if ( children.length > 1 ) {
  
  					// it seems like stacks will always be associated with a single layer. But just in case there are files
  					// where there are multiple layers per stack, we'll display a warning
  					console.warn( 'THREE.FBXLoader: Encountered an animation stack with multiple layers, this is currently not supported. Ignoring subsequent layers.' );
  
  				}
  
  				var layer = layersMap.get( children[ 0 ].ID );
  
  				rawClips[ nodeID ] = {
  
  					name: rawStacks[ nodeID ].attrName,
  					layer: layer,
  
  				};
  
  			}
  
  			return rawClips;
  
  		}
docs: parse nodes in FBXTree.Objects.AnimationStack. These are the top level node in the animation hierarchy. Each Stack node will be used to create a THREE.AnimationClip