ex 3.23 - abstraction
ex 3.23 - front-insert
ex 3.23 - I think it won't work
ex 3.23 - rewrite insert
ex 3.23 - front/rear insert
ex 3.23 - impl done
ex 3.23 - add some comments
ex 3.23 - done
3.3.3 - lookup
3.3.3 - my-assoc, few comments
3.3.3 - tables - done
3.3.3 2d-table impl
3.3.3 - 2d-table test ok
3.3.3 - creating local table (hold on)
3.3.3 - seperate table impl
3.3.3 - chanllenge - alternative 2d table impl
3.3.3 - local table - test passed
3.3.3 - creating local tables - done
ex 3.24 - done some test about normal table
ex 3.24 - done