ugin</a> and if false
is returned the next <a class="reference external" href="reference-Plugins.html#plugin">plugin</a> in the chain will receive it to
be able to handle it. This is not called for web seeds.
thus function may be called more than once per incoming message, but
only the last of the calls will the <tt class="docutils literal">body</tt> size equal the <tt class="docutils literal">length</tt>.
i.e. Every time another fragment of the message is received, this
function will be called, until final