static Object process(String processorID, Object in) {
  return process(processorID, in, "in");
}

static Object process(String processorID, Object in, String outVar) {
  try {
    Class processor = hotwire(processorID);
    set(processor, "in", in);
    call(processor, "main", new Object[] {new String[0]});
    return get(processor, outVar);
  } catch (Exception e) {
    throw new RuntimeException("Error in #" + parseSnippetID(processorID), e);
  }
}