def to_h
      h = {}
      to_hash(@root_node).each do |k, v|
        key = k.terminate(false).to_string
        h[key] = v
      end
      h
    end
def to_h
      h = {}
      to_hash(@root_node).each do |k, v|
        key = k.terminate(false).to_string
        h[key] = v
      end
      h
    end
Convert to hash.