// file will be in current program's cache dir
static File loadProgramDex(S snippetID) {
  snippetID = str(parseSnippetID(snippetID));
  File dexFile = getCacheProgramFile(snippetID + ".dex");
  saveBinaryFile(dexFile,
    loadBinaryPage(tb_mainServer() + "/dexcompile.php?id=" + psI(snippetID)));
  if (dexFile.exists())
    print("Dex downloaded to " + f2s(dexFile));
  ret dexFile;
}