# File lib/sass/tree/visitors/perform.rb, line 203
  def visit_debug(node)
    res = node.expr.perform(@environment)
    if res.is_a?(Sass::Script::Value::String)
      res = res.value
    else
      res = res.to_sass
    end
    if node.filename
      Sass::Util.sass_warn "#{node.filename}:#{node.line} DEBUG: #{res}"
    else
      Sass::Util.sass_warn "Line #{node.line} DEBUG: #{res}"
    end
    []
  end