format string normal_row with an dictionary containing 6 entries: return value of the function force_text with an argument bf_errors,
output . append ( normal_row % { 'errors' : force_text ( bf_errors ) , 'label' : force_text ( label ) , 'field' : six . text_type ( bf ) , 'help_text' : help_text , 'html_class_attr' : html_class_attr , 'field_name' : bf . html_name , } )