     or after each call. If <code class="computeroutput"><span class="identifier">write</span></code>
          returns no error and with zero <code class="computeroutput"><span class="identifier">zs</span><span class="special">.</span><span class="identifier">avail_out</span></code>,
          it must be called again after making room in the output buffer because
          there might be more output pending. The flush parameter may be <a class="link" href="../boost__beast__zlib__Flush.html" title="zlib::Fl