if (s.startsWith("!")) {
  S translator = s.substring(1);
  if (isSnippetID(translator)) {
    File x = tempDir();
    S oldText = getText();
    saveTextFile(new File(x, "main.java"), oldText);
    ArrayList<File> libraries_out = new ArrayList<File>();
    File y = cast call(getJavaX(), "applyTranslator", x, translator, "", libraries_out);
    S text = loadTextFile(new File(y, "main.java"));
    if (text == null)
      ret "hm.";
    boolean same = eq(oldText, text);
    setText(text);
    ret same ? "OK - no change" : "OK, applied !" + translator;
  }
}

Began life as a copy of #1001451