pos = indexIn(string, oldpos);
    } while (pos != -1);

    buf.append(string, oldpos, len);
    return buf.toString();
  }

  /**
   * Returns a substring of the input character sequence that omits all matching BMP characters from
   * the beginning and from the end of the string. For example:
   *
   * {@snippet :
   * CharMatcher.anyOf("ab").trimFrom("abacatbab")
   * }
   *