def uproot(tree):
        """
        Take a subranch of a tree and deep-copy the children
        of this subbranch into a new LabeledTree
        """
        uprooted = tree.copy()
        uprooted.parent = None
        for child in tree.all_children():
            uprooted.add_general_child(child)
        return uprooted
Take a subranch of a tree and deep-copy the children
        of this subbranch into a new LabeledTree