Lisp Hashtable默认的比较是用equa 函数，更换比较函数即可。
(setq table (make-hash-table)) => #<HASH-TABLE EQL 0/120 46142754>
(setf (gethash "one" table) 1) => 1
(gethash "one" table) => NIL, false
(setq table (make-hash-table :test 'equal)) => #<HASH-TABLE EQUAL 0/139 46145547>
(setf (gethash "one" table) 1) => 1
(gethash "one" table) => 1, T
(make-hash-table :rehash-size 1.5 :rehash-threshold 0.7)
