class Sass::Tree::Visitors::Convert

def visit_mixin(node)
  unless node.args.empty? && node.keywords.empty?
    args = node.args.map {|a| a.to_sass(@options)}.join(", ")
    keywords = node.keywords.map {|k, v| "$#{dasherize(k)}: #{v.to_sass(@options)}"}.join(', ')
    arglist = "(#{args}#{', ' unless args.empty? || keywords.empty?}#{keywords})"
  end
  "#{tab_str}#{@format == :sass ? '+' : '@include '}#{dasherize(node.name)}#{arglist}#{semi}\n"
end