rust rust-example-rendered'>
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>cell</span>::<span class='ident'>RefCell</span>;

<span class='kw'>let</span> <span class='ident'>x</span> <span class='op'>=</span> <span class='ident'>RefCell</span>::<span class='ident'>new</span>(<span class='number'>42</span>);

<span class='kw'>let</span> <span class='ident'>y</span> <span class='op'>=</span> <span class='ident'>x</span>.<span class='ident'>borrow_mut</span>();</pre>

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