nfo ">
<div class="info-desc">
<p><code class="code">add_channel&nbsp;b&nbsp;ic&nbsp;n</code> reads at most <code class="code">n</code> characters from the
   input channel <code class="code">ic</code> and stores them at the end of buffer <code class="code">b</code>.
   Raise <code class="code"><span class="constructor">End_of_file</span></code> if the channel contains fewer than <code class="code">n</code>
   characters. In this case, the characters are still added to
   the buffer, so as to avoid loss of 