# File lib/sass/tree/visitors/perform.rb, line 158
  def visit(node)
    return super(node.dup) unless @environment
    @environment.stack.with_base(node.filename, node.line) {super(node.dup)}
  rescue Sass::SyntaxError => e
    e.modify_backtrace(:filename => node.filename, :line => node.line)
    raise e
  end