#NEWLINE# def root_node( self , tree_id ) : #NEWLINE# #INDENT# '\n        Returns the root node of the tree with the given id.\n        ' #NEWLINE# return self . get ( ** { #NEWLINE# #INDENT# self . tree_id_attr : self , #NEWLINE# ( '%s__isnull' % self . parent_attr ) : True , #NEWLINE# #UNINDENT# } )