them. </p>
<p>The function object is invoked for each entity. It is provided with the entity itself and a set of references to non-empty components. The <em>constness</em> of the components is as requested.<br  />
 The signature of the function must be equivalent to one of the following forms:</p>
<div class="fragment"><div class="line">void(<span class="keyword">const</span> <a class="code hl_typedef" href="#abb8a3829dcd9e0699bb39e52ba42c9c1">entity_type</a>, Type &amp;...);</div>
<div class="line">void(Ty