 (reading input without producing any output) except
          when forced to flush. One or both of the following actions are performed:
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              Decompress more input starting at <code class="computeroutput"><span class="identifier">zs</span><span class="special">.</span><span class="identifier">next_in</span></code>
              and update <code class="computeroutput"><span class="i