笨办法学pythoon 习题48 词汇扫描器代码 。 单元测试代码有微调。 常见错误 1. 'module' object has no attribute 'scan' 在测试文件里改成from ex48.lexicon import Lexicon 2.unbound method scan() must be called with Lexicon instance as first argument (got str instance instead) 类在引用前没有实例化，将测试文件
1-50课课后习题和答案，编号清楚，有目录，方便查看和学习。
python课后题
1-50 exercises and answers after class, with clear numbers and catalogues, convenient for viewing and learning.
Python after class questions
