class Sass::Script::Tree::MapLiteral

def to_sass(opts = {})
  return "()" if pairs.empty?
  to_sass = lambda do |value|
    if value.is_a?(ListLiteral) && value.separator == :comma
      "(#{value.to_sass(opts)})"
    else
      value.to_sass(opts)
    end
  end
  "(" + pairs.map {|(k, v)| "#{to_sass[k]}: #{to_sass[v]}"}.join(', ') + ")"
end