def norm_mac(mac):
    """Normalizes a MAC address from pypowervm format to OpenStack.

    That means that the format will be converted to lower case and will
    have colons added.

    :param mac: A pypowervm mac address.  Ex. 1234567890AB
    :return: A mac that matches the standard neutron format.
             Ex. 12:34:56:78:90:ab
    """
    mac = mac.lower().replace(':', '')
    return ':'.join(mac[i:i + 2] for i in range(0, len(mac), 2))