You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: attrib_namespace.rb
    path of file: ./repos/open-build-service/src/api/app/models
    
    the code of the file until where you have to start completion: # Specifies own namespaces o
    
  def update_from_xml(node)
    transaction do
      attrib_namespace_modifiable_bies.delete_all
      # store permission settings
      node.elements('modifiable_by') { |element| create_one_rule(element) }
      save
    end
  end