code: def diff_trees(left, right, diff_options=None, formatter=None):
      
      if formatter is not None:
          formatter.prepare(left, right)
      if diff_options is None:
          diff_options = {}
      differ = diff.Differ(**diff_options)
      diffs = differ.diff(left, right)
  
      if formatter is None:
          return list(diffs)
  
      return formatter.format(diffs, left)
docs: Takes two lxml root elements or element trees