*                  str -> str.substring(1).chars().mapToObj(c -> (char) c));
   *
   * // is equivalent to
   *
   * static final ImmutableListMultimap<Character, Character> FIRST_LETTER_MULTIMAP =
   *     ImmutableListMultimap.<Character, Character>builder()
   *         .putAll('b', Arrays.asList('a', 'n', 'a', 'n', 'a'))
   *         .putAll('a', Arrays.asList('p', 'p', 'l', 'e'))
   *         .putAll('c', Arrays.asList('a', 'r', 'r', 'o', 't'))