in what we're solving (Rationale); then how we solve it (Design). The latter is much simpler, we think, to understand then the former. Hence apologies in advance for the length of "Rationale" section.</p>
<h3>Rationale</h3>
<p >Consider a particular <a class="el" href="classipc_1_1session_1_1Client__session__impl.html" title="Internal, non-movable pImpl-lite implementation of Client_session_mv class template.">Client_session_impl</a> + <a class="el" href="classipc_1_1session_1_1Server__session__impl.html" t