static L<S> tok_moveImportsUp(L<S> tok) {
  new StringBuilder buf;
  
  // scan imports on top
  int i;
  new Set<S> have;
  for (i = 1; i < l(tok); i += 2)
    if (eq(tok.get(i), 'import)) {
      int j = indexOf(tok, i+2, ";");
      if (j < 0) break;
      S s = joinSubList(tok, i, j+1);
      have.add(s);
      i = j;
    }
  
  // scan imports in text
  for (; i < l(tok); i += 2)
    if (eq(tok.get(i), 'import)) {
      int j = indexOf(tok, i+2, ";");
      if (j < 0) continue; // huh?
      S s = joinSubList(tok, i, j+1);
      print("Found import at " + i + ": " + s);
      if (!have.contains(s)) {
        buf.append(s).append("\n");
        have.add(s);
      }
      replaceTokens_reTok(tok, i, j+1, "");
    }
    
  if (nempty(buf)) {
    if (l(tok) == 1) addAll(tok, "", "");
    tok.set(1, str(buf)+tok.get(1));
    reTok(tok, 1, 2);
  }
    
  ret tok;
}