code: private void consumeKeyword(char first, char[] expected) throws JsonParserException {
      for (int i = 0; i < expected.length; i++)
        if (advanceChar() != expected[i])
          throw createHelpfulException(first, expected, i);
  
      // The token should end with something other than an ASCII letter
      if (isAsciiLetter(peekChar()))
        throw createHelpfulException(first, expected, expected.length);
    }
docs: Expects a given string at the current position.