class Sass::Script::Parser

def special_fun
  return paren unless tok = try_tok(:special_fun)
  first = node(Script::String.new(tok.value.first))
  Sass::Util.enum_slice(tok.value[1..-1], 2).inject(first) do |l, (i, r)|
    Script::Interpolation.new(
      l, i, r && node(Script::String.new(r)),
      false, false)
  end
end