def find_next_ready_and_remove(g, node):
    """Given a recently satisfied node,
    return any successors with in_degree 1.
    Then remove node from g immediately.
    """
    ready = set()
    for n in g.successors(node):
        if 1 == g.in_degree(n):
            ready.add(n)
    g.remove_node(node)
    return ready