def user_object_path
      arr = []
      arr << self.user_object.to_s
      traverse_up do |e|
        arr << e.user_object.to_s
      end
      arr.reverse!
    end
def user_object_path
      arr = []
      arr << self.user_object.to_s
      traverse_up do |e|
        arr << e.user_object.to_s
      end
      arr.reverse!
    end
returns an array of user_objects for the current node
 starting from root, ending in the current one. The last node
 represents this node.
 @return [Array] Strings[]