A CTree = (Node x [CTree]) is a Node associated with a list of subtrees called branches.
Tree putSubFolder(Tree folder, Tree path, Tree item)
Tree uiWidget(Tree label, Tree varname, Tree sig)
bool isUiWidget(Tree t, Tree &label, Tree &varname, Tree &sig)
Tree uiFolder(Tree label, Tree elements=nil)
Tree branch(int i) const
return the ith branch (subtree) of a tree