@staticmethod
def sector_hex_to_subsector_hex(hex_id):
    """Transform sector hex_id to subsector hex_id"""
    hex_id_col = int(hex_id[:2])
    hex_id_row = int(hex_id[2:])
    col = hex_id_col % 8
    row = hex_id_row % 10
    if col == 0:
        col = 8
    if row == 0:
        row = 10
    return '{0:02d}{1:02d}'.format(col, row)
