// split smth like "if * then *" into "if *" and "then *"
// returns null if no split
// now also for NL trees
static L<Lisp> snlSplitOps(Lisp code) {
  new L<Lisp> out;
  
  if (code.is("[]")) {
    // NL
    
    if ((code.size() & 1) != 0) ret null;
    for (int i = 0; i < code.size(); i += 2) {
      Lisp op = code.get(i), arg = code.get(i+1);
      if (!op.isLeaf() || !isExtendedIdentifier(op.head)) ret null;
      out.add(lisp(op + " *", nlUnbracket(arg)));
    }
    
    ret out;
  }
  
  S ops = code.head;
  L<S> tok = codeTokensOnly(javaTok(ops));
  if ((l(tok) & 1) != 0) ret null;
  for (int i = 0; i < l(tok); i += 2) {
    S op = tok.get(i);
    if (!isIdentifier(op) || neq("*", tok.get(i+1))) ret null;
    out.add(lisp(op + " *", code.get(i/2)));
  }
  //print("splitOps => " + structure(out));
  ret out;
}