#NEWLINE# def guard_index( self , idx , msg ) : #NEWLINE# #INDENT# '\n        Raise an error if the index is out of bounds.\n        ' #NEWLINE# with self . _builder . if_then ( self . is_out_of_bounds ( self ) , likely = False ) : #NEWLINE# #INDENT# self . _context . call_conv . return_user_exc ( self . _builder , IndexError , ( msg , ) )