# File lib/sass/tree/visitors/perform.rb, line 143
  def visit_debug(node)
    res = node.expr.perform(@environment)
    res = res.value if res.is_a?(Sass::Script::String)
    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