code: private static Pattern notChar2(final char c1, final char c2) {
      return new Pattern() {
        @Override public int match(CharSequence src, int begin, int end) {
          if (begin == end - 1) return 1;
          if (begin >= end) return MISMATCH;
          if (src.charAt(begin) == c1 && src.charAt(begin + 1) == c2) return Pattern.MISMATCH;
          return 1;
        }
      };
    }
docs: Matches a character if the input has at least 1 character, or if the input has at least 2
  characters with the first 2 characters not being {@code c1} and {@code c2}.
  
  @return the Pattern object.