def _possible_string_format_functions(format_):
 (yield (lambda format_, val: format(val, format_)))
 (yield (lambda format_, val: format_.format(val)))
 (yield (lambda format_, val: (format_ % val)))

def _possible_string_format_functions ( format_ ) : ( yield ( lambda format_ , val : format ( val , format_ ) ) ) ( yield ( lambda format_ , val : format_ . format ( val ) ) ) ( yield ( lambda format_ , val : ( format_ % val ) ) )
iterate through possible string-derived format functions .