元素不能用以下关键字，否则会混淆。
Expecting ‘TESTSTR’, ‘PIPE’, ‘DOWN’, ‘NUM’, ‘COMMA’, ‘ALPHA’, ‘COLON’, ‘MINUS’, ‘BRKT’, ‘DOT’, ‘PUNCTUATION’, ‘UNICODE_TEXT’, ‘PLUS’, ‘EQUALS’, ‘MULT’, ‘UNDERSCORE’, got ‘end’