tem">
            The extraction of the body is conflated with the asynchronous model.
          </li>
<li class="listitem">
            No way to define an allocator for the container used when extracting
            the body.
          </li>
<li class="listitem">
            A body can only be extracted once, limiting the use of this container
            when using a functional programming style.
          </li>
<li class="listitem">
            Setting the body requires either a vector or a <code class=