e expression
  assigned to it. Thus:</p>
<pre><code><font color="#000000">    <span class=identifier>rule</span><span class=special>&lt;&gt; </span><span class=identifier>r </span><span class=special>= </span><span class=identifier>i </span><span class=special>| </span><span class=identifier>j </span><span class=special>&gt;&gt; </span><span class=identifier>k</span><span class=special>;  </span><span class=comment>// where i, j, and k are chlit&lt;&gt; objects</span></font></code></pre>
<p>It might not be 