code> according to the format string <code class="code">format</code>, and
   outputs the resulting string on the channel <code class="code">outchan</code>.
<p>

   The format string is a character string which contains two types of
   objects: plain characters, which are simply copied to the output
   channel, and conversion specifications, each of which causes
   conversion and printing of arguments.
</p><p>

   Conversion specifications have the following form:
</p><p>

   <code class="code">%&nbsp;[flag