her this instance is a end of input </span>
        <span class="comment">// iterator.</span>
        <span class="comment">//</span>
        <span class="comment">//   mp:    is a reference to the whole multi_pass instance</span>
        <span class="comment">//</span>
        <span class="comment">// This method is expected to return true if the end of input is </span>
        <span class="comment">// reached. </span>
        <span class="keyword">template</span> <span class="special">&lt;</span><span cla