docs: def tree_compare(self, othertree, vntree_meta=False):
          """Compare the (sub-)tree rooted at `self` with another tree.
  
          `tree_compare` converts the trees being compared into JSON string
          representations, and uses `difflib.SequenceMatcher().ratio()` to
          calculate a measure of the similarity of the strings.
  
          :param othertree: the other tree for comparison.
          :type othertree: Node
          :param vntree_meta: include private vntree metadata in comparison.
          :type vntree_meta: bool
          :returns: similarity of the trees as a number between 0 and 1. 
          :rtype: float 
          """
          return SequenceMatcher(None, 
                  json.dumps(self.to_treedict(vntree_meta=vntree_meta), default=str), 
                  json.dumps(othertree.to_treedict(vntree_meta=vntree_meta), default=str)
                  ).ratio()