code: @Cached
      @DontLabel
      public Rule ignoreCase(final char... characters)
      {
          if (characters.length == 1)
              return ignoreCase(characters[0]); // optimize one-char strings
          return new StringIgnoreCaseMatcher(new String(characters));
      }
docs: Match a sequence of characters as a string literal (case insensitive)
  
  @param characters the characters of the string to match
  @return a rule