class Sass::Engine

def check_for_no_children(node)
  return unless node.is_a?(Tree::RuleNode) && node.children.empty?
  Haml::Util.haml_warn(<<WARNING.strip)
ING on line #{node.line}#{" of #{node.filename}" if node.filename}:
 selector doesn't have any properties and will not be rendered.
ING
end