e the protothreads are</span>
<span class="comment"> * initialized and scheduled. First, however, we define the</span>
<span class="comment"> * protothread state variables pt1 and pt2, which hold the state of</span>
<span class="comment"> * the two protothreads.</span>
<span class="comment"> */</span>
<span class="keyword">static</span> <span class="keyword">struct </span>pt pt1, pt2;
<span class="keywordtype">int</span>
main(<span class="keywordtype">void</span>)
{
  <span class="comment">/* Initi