class Nokogiri::XML::Node

def replace(new_node)
  if new_node.is_a?(Document) || !new_node.is_a?(XML::Node)
    raise ArgumentError, <<-EOERR
eplace requires a Node argument, and cannot accept a Document.
robably want to select a node from the Document with at() or search(), or create a new Node via Node.new().)
    EOERR
  end
  replace_with_node new_node
end