class Sass::Tree::Visitors::CheckNesting

def invalid_import_parent?(parent, child)
  unless (@parents.map {|p| p.class} & INVALID_IMPORT_PARENTS).empty?
    return "Import directives may not be used within control directives or mixins."
  end
  return if parent.is_a?(Sass::Tree::RootNode)
  return "CSS import directives may only be used at the root of a document." if child.css_import?
rescue Sass::SyntaxError => e
  e.modify_backtrace(:filename => child.imported_file.options[:filename])
  e.add_backtrace(:filename => child.filename, :line => child.line)
  raise e
end