/** True if the node contains any blocker which is not included in the \a selector list */
    public bool NodeContainsAnyExcept (GraphNode node, List<SingleNodeBlocker> selector) {
        List<SingleNodeBlocker> blockersInNode;
        if (!blocked.TryGetValue(node, out blockersInNode)) {
            return false;
        }

        for (int i = 0; i < blockersInNode.Count; i++) {
            var inNode = blockersInNode[i];
            bool found = false;
            for (int j = 0; j < selector.Count; j++) {
                // Need to use ReferenceEquals because this code may be called from a separate thread
                // and the equality comparison that Unity provides is not thread safe
                if (System.Object.ReferenceEquals(inNode, selector[j])) {
                    found = true;
                    break;
                }
            }
            if (!found) return true;
        }
        return false;
    }