def deep_clone
      cl = clone()
      each do |child|
        if child.kind_of? Parent
          cl << child.deep_clone
        else
          cl << child.clone
        end
      end
      cl
    end
def deep_clone
      cl = clone()
      each do |child|
        if child.kind_of? Parent
          cl << child.deep_clone
        else
          cl << child.clone
        end
      end
      cl
    end
Deeply clones this object.  This creates a complete duplicate of this
 Parent, including all descendants.