static Set<S> collectSnippetIDsInTranspiledSnippet(S snippetID) {
  if (isImageSnippetID(snippetID)) ret new Set;
  S src = getServerTranspiled2(snippetID);
  Set<S> set = collectSnippetIDsInText(src);
  addAll(set, map fsI(regexpAll("[0-9]+", firstLine(src)));
  ret set;
}