6; // エラー!
}</span><pre class='rust rust-example-rendered'>
<span class='kw'>let</span> <span class='ident'>x</span> <span class='op'>=</span> <span class='number'>5</span>;
<span class='ident'>x</span> <span class='op'>=</span> <span class='number'>6</span>; <span class='comment'>// エラー!</span></pre>

<!-- We can introduce mutability with the `mut` keyword: -->

<p><code>mut</code> キーワードによりミュータビリティを導入できます:</p>

<span class='rusttest'>fn main() {
   