code: private static int indexOf(CharSequence cs, int searchChar, int start) {
      if (cs instanceof String) {
        return ((String) cs).indexOf(searchChar, start);
      } else {
        int sz = cs.length();
        if (start < 0) {
          start = 0;
        }
        for (int i = start; i < sz; i++) {
          if (cs.charAt(i) == searchChar) { return i; }
        }
        return -1;
      }
    }
docs: <p>
  Finds the first index in the {@code CharSequence} that matches the specified character.
  </p>
  
  @param cs the {@code CharSequence} to be processed, not null
  @param searchChar the char to be searched for
  @param start the start index, negative starts at the string start
  @return the index where the search char was found, -1 if not found