span class="identifier">v</span></code> in
        a type <code class="computeroutput"><span class="identifier">T</span></code> -either exact or
        inexact-, is any of the adjacents of <code class="computeroutput"><span class="identifier">V</span></code>
        in that type, that is, if <code class="computeroutput"><span class="identifier">v</span><span class="special">==</span><span class="identifier">prev</span></code>
        or <code class="computeroutput"><span class="identifier">v</span><span cl