version, there may be
    the special flag <code class="code">_</code>: the conversion that follows occurs as usual,
    but the resulting value is discarded.
    For instance, if <code class="code">f</code> is the function <code class="code"><span class="keyword">fun</span>&nbsp;i&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;i&nbsp;+&nbsp;1</code>, and <code class="code">s</code> is the
    string <code class="code"><span class="string">"x&nbsp;=&nbsp;1"</span></code>, then <code class="code"><span cla