def transform_octet_to_mac(octet_string):
    """
    Transforms SNMP Octet string to MAC address  separated by ':'
    Args:
        octet_string: SNMP Octet string

    Returns:
        MAC address separated by ':'
    """
    mac_address = ''

    if isinstance(octet_string, bytes):
        mac_address = u':'.join(u'{:02x}'.format(field) for field in octet_string)
    else:
        mac_address = u':'.join(u'{:02x}'.format(ord(field)) for field in octet_string)

    return mac_address.upper()