class Sass::Tree::Visitors::Perform

def visit_mixindef(node)
  env = Sass::Environment.new(@environment, node.options)
  @environment.set_local_mixin(node.name,
    Sass::Callable.new(node.name, node.args, node.splat, env,
                       node.children, node.has_content, "mixin", :stylesheet))
  []
end