def METHOD_NAME(self, link_peer: str, link_peer_channel_group_id: int, link_channel_description: str) -> str:
    """
    Implementation of custom code similar to jinja:
    custom_templates/interface_descriptions/underlay/port-channel-interfaces.j2
    """
    if link_channel_description is not None:
        link_channel_description = str(link_channel_description).upper()
        return f"{self._custom_description_prefix}_{link_channel_description}_Po{link_peer_channel_group_id}"
    link_peer = str(link_peer).upper()
    return f"{self._custom_description_prefix}_{link_peer}_Po{link_peer_channel_group_id}"