computeroutput"><span class="identifier">seq</span></code>
            if <code class="computeroutput"><span class="identifier">seq</span></code> is mutable and
            <code class="computeroutput"><span class="identifier">e</span> <span class="special">=</span>
            <span class="identifier">o</span></code>, where <code class="computeroutput"><span class="identifier">e</span></code>
            is the first element in the sequence, is a valid expression. Else, returns
            a type convertab