uteroutput"><span class="identifier">S</span><span class="special">-&gt;</span><span class="identifier">T</span></code>
        and <code class="computeroutput"><span class="identifier">T</span><span class="special">-&gt;</span><span class="identifier">S</span></code>, it is effectively indicating a type
        which can represent all the values of the subtype. Consequently, if a conversion
        <code class="computeroutput"><span class="identifier">X</span><span class="special">-&gt;</span><span class="