class_docstr: An AttrTree offers convenient, multi-level attribute access for
  collections of objects. AttrTree objects may also be combined
  together using the update method or merge classmethod. Here is an
  example of adding a ViewableElement to an AttrTree and accessing it:
  
  >>> t = AttrTree()
  >>> t.Example.Path = 1
  >>> t.Example.Path                             #doctest: +ELLIPSIS
  1
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code: def root(self):
      root = self
      while root.parent is not None:
          root = root.parent
      return root
  
imports: from .None import util
  from .pprint import PrettyPrinter
label_desc: Use image node_id 4 for calling the AttrTree obj's underlying member method code with example usage: obj.root() and returns: root