def diskcache_expand(d):
    """return  list of strings described by d, where 
        d is dict with keys
    {"directory", "frame_type", "site", "dur", "ext", "segmentlist"}
    """
    for dc_seg in d['segmentlist']:
        for gps in range(dc_seg[0], dc_seg[1], d['dur']):
            lfn = '-'.join([d['site'], d['frame_type'], str(gps), str(d[
                'dur'])]) + d['ext']
            yield '/'.join([d['directory'], lfn])
