static void assertLispScriptSucceeds(S script) {
  int i = 0;
  L<Lisp> lines = linesToLisp(script);
  for (Lisp cmd : lines) {
    O executor = getLispExecutor(cmd.head);
    if (executor == null) fail("No executor for " + cmd);
    callF(executor, cmd);
    print("Executed line " + (++i) + " of " + l(lines));
  }
}