class Sass::Script::Tree::Funcall

def deep_copy
  node = dup
  node.instance_variable_set('@args', args.map {|a| a.deep_copy})
  copied_keywords = Sass::Util::NormalizedMap.new
  @keywords.as_stored.each {|k, v| copied_keywords[k] = v.deep_copy}
  node.instance_variable_set('@keywords', copied_keywords)
  node
end