joint.all.js
function inSubtree(tree, n, root) {
  return (tree.node(root).low <= tree.node(n).lim &&
          tree.node(n).lim <= tree.node(root).lim);
}
function inSubtree(tree, n, root) {
  return (tree.node(root).low <= tree.node(n).lim &&
          tree.node(n).lim <= tree.node(root).lim);
}
/*
Return whether n is a node in the subtree with the given
root.