#NEWLINE# def __init__( self , * args , **kwargs ) : #NEWLINE# #INDENT# super ( ListMixin , self ) . __init__ ( * args , ** kwargs ) #NEWLINE# get_items = getattr ( self , 'get_items' , None ) #NEWLINE# render = getattr ( self , 'render' , None ) #NEWLINE# if ( ( not callable ( get_items ) ) or ( not callable ( self ) ) ) : #NEWLINE# #INDENT# raise Exception ( 'bases on ListWidgetMixin must have implemented get_items or render method' )