def METHOD_NAME(self, recipe):
    """
    Historical remembered individuals can have a node with a single descendant
    """
    for result in recipe["results"]:
        for ts in result.get_ts():
            num_unary_nodes = 0
            for tree in ts.trees():
                for n in tree.nodes():
                    if tree.num_children(n) == 1 and tree.parent(n) >= 0:
                        assert ts.node(n).individual >= 0  # has an individual
                        ind = ts.individual(ts.node(n).individual)
                        assert ts.node(n).is_sample()
                        assert (ind.flags & pyslim.INDIVIDUAL_REMEMBERED) != 0
                        num_unary_nodes += 1
            assert num_unary_nodes > 0