Optional elbowThe component used as an Elbow: the tree-shape part when this node is the last descendent of it's parent node.
the node key that the current tree-shape is used for
Optional pipeThe component used as a Pipe; the tree-shape part when some ancestor of this node has siblings below it
Optional skipskips the first item - use this if you don't want a stray pipe or elbow on your root.
Optional spacerThe component used as a spacer in the tree
Optional teeThe component used as a Tee; the tree-shape part next to the node and the node has additional siblings below it.
Example