How to use the fileseq.utils.pad function in Fileseq

def _do_pad(match):
            """
            Substitutes padded for unpadded frames.
            """
            result = list(match.groups())
            result[1] = pad(result[1], zfill)
            if result[4]:
                result[4] = pad(result[4], zfill)
            return ''.join((i for i in result if i))
        return PAD_RE.sub(_do_pad, frange)

"""
        Private method: builds a proper and padded
        frame range string.

        Args:
            start (int): first frame
            stop (int or None): last frame
            stride (int or None): increment
            zfill (int): width for zero padding

        Returns:
            str:
        """
        if stop is None:
            return ''
        pad_start = pad(start, zfill)
        pad_stop = pad(stop, zfill)
        if stride is None or start == stop:
            return '{0}'.format(pad_start)
        elif abs(stride) == 1:
            return '{0}-{1}'.format(pad_start, pad_stop)
        else:
            return '{0}-{1}x{2}'.format(pad_start, pad_stop, stride)

Args:
            frames (collections.Iterable): sequence of frames to process
            sort (bool): sort the sequence before processing
            zfill (int): width for zero padding
            compress (bool): remove any duplicates before processing

        Returns:
            str:
        """
        if compress:
            frames = unique(set(), frames)
        frames = list(frames)
        if not frames:
            return ''
        if len(frames) == 1:
            return pad(frames[0], zfill)
        if sort:
            frames.sort()
        ret = ','.join(FrameSet.framesToFrameRanges(frames, zfill))
        return future.utils.native_str(ret)

Private method: builds a proper and padded
        frame range string.

        Args:
            start (int): first frame
            stop (int or None): last frame
            stride (int or None): increment
            zfill (int): width for zero padding

        Returns:
            str:
        """
        if stop is None:
            return ''
        pad_start = pad(start, zfill)
        pad_stop = pad(stop, zfill)
        if stride is None or start == stop:
            return '{0}'.format(pad_start)
        elif abs(stride) == 1:
            return '{0}-{1}'.format(pad_start, pad_stop)
        else:
            return '{0}-{1}x{2}'.format(pad_start, pad_stop, stride)

def _do_pad(match):
            """
            Substitutes padded for unpadded frames.
            """
            result = list(match.groups())
            result[1] = pad(result[1], zfill)
            if result[4]:
                result[4] = pad(result[4], zfill)
            return ''.join((i for i in result if i))
        return PAD_RE.sub(_do_pad, frange)