Returns mac address.

def mac_addr_info():
    """Returns mac address.
    """
    mac = get_mac()
    if mac == get_mac():  # not random generated
        hexa = '%012x' % mac
        value = ':'.join(hexa[i:i+2] for i in range(0, 12, 2))
    else:
        value = None
    return {'mac': value}