private static boolean isIdentifier(String lexeme) {
		char firstChar = lexeme.charAt(0);

		if (!(Character.isLetter(firstChar) || firstChar == '_')) {
			return false;
		}
		
		char[] lexemeArray = lexeme.toCharArray();
		for (char c : lexemeArray) {
			if (!(Character.isDigit(c) || Character.isLetter(c) || c == '_')) {
				return false;
			}
		}
		return true;
	}