// optional parameter trace_out for collecting the reference tree
// optional parameter exclude: set of excluded
static Set<S> recursivelyCollectSnippetIDsFromTranspiled_multi(Cl<S> snippetIDs, O... _) {
  Set<S> exclude = cast optPar exclude(_);
  ret transitiveHullOfFunction_multipleInputs(func(S snippetID) -> Collection<S> {
    collectionMinusSet(collectSnippetIDsInTranspiledSnippet(snippetID), exclude)
  }, snippetIDs, _);
}

Began life as a copy of #1022617