def reformat_mac(mac: str) -> str:
    """
    Reformat MAC address to all lowercase with
     dashes separating octets e.g. 1a-2a-a3-b5-e4-2a
    :param mac: MAC address to format
    :return: reformatted MAC as string
    """
    mac = mac.replace('-', '').replace(':', '')
    mac = '-'.join(mac[i:i + 2] for i in range(0, 12, 2)).lower()
    return mac