class="lineno">  421</span>&#160;    <span class="keywordflow">if</span> (primes.<a class="code" href="classhelib_1_1_index_set.html#a018572f1e76bc3c9750491f2cf02c7ca">card</a>() == 0) {</div>
<div class="line"><a name="l00422"></a><span class="lineno">  422</span>&#160;      <span class="keywordflow">throw</span> <a class="code" href="classhelib_1_1_logic_error.html">LogicError</a>(</div>
<div class="line"><a name="l00423"></a><span class="lineno">  423</span>&#160;          <span class="stringliteral">&qu