 `else`
blocks, `calculating slowly...` appears only once and only when needed. The
`Cacher` takes care of the logic necessary to ensure we aren’t calling the
expensive calculation more than we need to so `generate_workout` can focus on
the business logic.
-->
<p>リスト13-2の<code>main</code>関数とともにこのプログラムを走らせてみてください。
<code>simulated_user_specified_value</code>と<code>simulated_random_number</code>変数の値を変えて、
いろんな<code>if</code>