ata</span>.<span class='ident'>lock</span>().<span class='ident'>unwrap</span>();
    <span class='ident'>data</span>[<span class='ident'>i</span>] <span class='op'>+=</span> <span class='number'>1</span>;
});</pre>

<!-- First, we call `lock()`, which acquires the mutex's lock. Because this may fail, -->

<!-- it returns an `Result<T, E>`, and because this is just an example, we `unwrap()` -->

<!-- it to get a reference to the data. Real code would have more robust error handling -->

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