int pos = indexIn(string);
    if (pos == -1) {
      return string;
    }
    char[] chars = string.toCharArray();
    chars[pos] = replacement;
    for (int i = pos + 1; i < chars.length; i++) {
      if (matches(chars[i])) {
        chars[i] = replacement;
      }
    }
    return new String(chars);
  }

  /**

    int pos = indexIn(string);
    if (pos == -1) {
      return string;
    }
    char[] chars = string.toCharArray();
    chars[pos] = replacement;
    for (int i = pos + 1; i < chars.length; i++) {
      if (matches(chars[i])) {
        chars[i] = replacement;
      }
    }
    return new String(chars);
  }

  /**

   *     Stream.of("banana", "apple", "carrot", "asparagus", "cherry")
   *         .collect(
   *             flatteningToMultimap(
   *                  str -> str.charAt(0),
   *                  str -> str.substring(1).chars().mapToObj(c -> (char) c),
   *                  MultimapBuilder.linkedHashKeys().arrayListValues()::build));
   *
   * // is equivalent to
   *
   * static final ListMultimap<Character, Character> FIRST_LETTER_MULTIMAP;