us avoid having a mutable intermediate `results` vector. The
functional programming style prefers to minimize the amount of mutable state to
make code clearer. Removing the mutable state might enable a future enhancement
to make searching happen in parallel, because we wouldn’t have to manage
concurrent access to the `results` vector. Listing 13-29 shows this change:
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<p>イテレータアダプタメソッドを使用して、このコードをもっと簡潔に書くことができます。そうす�