@classmethod
def to_string_seg(cls, diar):
    """
        transform a diarization into a string
        :param diar: a diarization
        :return: a string
        """
    lst = []
    for segment in diar:
        gender = 'U'
        if diar._attributes.exist('gender'):
            gender = segment['gender']
        env = 'U'
        if diar._attributes.exist('env'):
            env = segment['env']
        channel = 'U'
        if diar._attributes.exist('channel'):
            channel = segment['channel']
        lst.append('{:s} 1 {:d} {:d} {:s} {:s} {:s} {:s}\n'.format(segment[
            'show'], segment['start'], segment['stop'] - segment['start'],
            gender, channel, env, segment['cluster']))
    return lst
