def METHOD_NAME(cmd, prefix, namespace, **kwargs):  # pylint: disable=unused-argument
    """Return Kubernetes versions available for upgrading an existing cluster."""
    resource_group = getattr(namespace, 'resource_group_name', None)
    name = getattr(namespace, 'name', None)
    return get_k8s_upgrades(cmd.cli_ctx, resource_group, name) if resource_group and name else None