lass="kw">type</span> <span class="prelude-val">Err</span> <span class="op">=</span> <span class="ident">value</span>::<span class="ident">Error</span>;

    <span class="kw">fn</span> <span class="ident">from_str</span>(<span class="ident">s</span>: <span class="kw-2">&amp;</span><span class="ident">str</span>) <span class="op">-&gt;</span> <span class="prelude-ty">Result</span><span class="op">&lt;</span><span class="self">Self</span>, <span class="self">Self</span>::<span class="prelude-val">Err</span><s