docs: private static Pair pair(String string, char separator)
    {
      int separatorIndex = string.indexOf(separator);
      if(separatorIndex == -1) {
        throw new BugError("Missing pair separator. Cannot initialize pair instance.");
      }
      final String first = string.substring(0, separatorIndex).trim();
      final String second = string.substring(separatorIndex + 1).trim();
      return new Pair(first, second);
    }