// nodeMatcher: func(WebNode, WebNode) -> double
static double web_matchAllPerms_x_bestScore(Web patternWeb, Web inputWeb, O nodeMatcher) {
  L<WebNode> patternNodes = web_nodes(patternWeb);
  L<WebNode> inputNodes = web_nodes(inputWeb);
  if (l(patternNodes) != l(inputNodes))
    ret Double.NaN;
    //fail("Can't match, differing number of nodes: " + l(patternNodes) + "/" + l(inputNodes));
  
  LL<WebNode> perms = allPermutations(inputNodes);
  new Best<L<WebNode>> best;
  for (L<WebNode> perm : perms)
    best.put(perm, web_matchNodeLists_x(patternNodes, perm, nodeMatcher));
  ret best.getScore();
}