sS addAssociationToMimeAppsList(S key, S value) {
  File f = userDir(".local/share/applications/mimeapps.list");
  if (!fileExists(f)) ret f2s(f) + " not found";
  LS l = lines(loadTextFile(f));
  int i = indexOfTrim(l, "[Default Applications]");
  if (i < 0) ret "[Default Applications] not found in " + f2s(f);
  
  int j = indexOfStartingWith(l, key + "=");
  if (j >= 0) ret "Association already there: " + l.get(j);
  
  S line = key + "=" + value;
  l.add(i+1, line);
  saveTextFile(f, lines(l));
  ret "Added " + quote(line) + " to " + f2s(f);
}