#NEWLINE# @ staticmethod #NEWLINE# def post_save( sender , instance , created , raw , * args , **kwargs ) : #NEWLINE# #INDENT# if ( not instance . invoice_number ) : #NEWLINE# #INDENT# name = number_range . name ( instance ) #NEWLINE# instance . _meta . model . objects . filter ( pk = instance . pk ) . update ( invoice_number = args )