must be followed by a digit.
      </p>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
          In <span class="emphasis"><em>Spirit.Qi</em></span>, we use the <code class="computeroutput"><span class="special">&gt;&gt;</span></code>
          for sequences since C++ does not allow juxtaposition, while in <span class="emp