exception if the header does not exist
        or contains an invalid value)
</p></div></div><div class="top"><p class="src"><a name="v:getQueue" class="def">getQueue</a> ::  Message m -&gt; IO String</p><div class="doc"><p>Get Queue name from headers
   (and throw an exception if the header does not exist)
</p></div></div><div class="top"><p class="src"><a name="v:getChannel" class="def">getChannel</a> ::  Message m -&gt; IO String</p><div class="doc"><p>Get Reply queue (channel) from headers
   (and throw