wish to defer the choice of the Body template type
        until after the header is available. Then, a body type may be chosen depending
        on the header contents. For example, depending on the verb, target path,
        or target query parameters. To accomplish this, a parser is declared to read
        in the header only, using a trivial body type such as <a class="link" href="../ref/boost__beast__http__empty_body.html" title="http::empty_body"><code class="computeroutput"><span class="identifier">e