ion to stand in for a hypothetical
calculation that takes about 2 seconds to run</span>
-->
<p><span class="caption">リスト13-1: 実行に約2秒かかる架空の計算の代役を務める関数</span></p>
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Next is the `main` function that contains the parts of the workout app
important for this example. This function represents the code that the app will
call when a user asks for a workout plan. Because the interaction with the
app’s frontend isn’t relevant to the use of closures, we’ll hard