an><span class="o">?</span><span class="id">pi</span> <span class="o">?*?</span> <span class="n">2</span><span class="pn">)</span> <span class="o">|&gt;</span> <span onmouseout="hideTip(event, 'fs15', 35)" onmouseover="showTip(event, 'fs15', 35)" class="fn">printfn</span> 
  <span class="k">let</span> <span onmouseout="hideTip(event, 'fs16', 36)" onmouseover="showTip(event, 'fs16', 36)" class="id">sin</span> <span class="o">=</span> <span onmouseout="hideTip(event, 'fs13', 37)" onmouseover="showTip(event, '