ntained</em></span> in a range <code class="computeroutput"><span class="identifier">Y</span></code>,
        in which case it is said that <code class="computeroutput"><span class="identifier">X</span></code>
        is enclosed by <code class="computeroutput"><span class="identifier">Y</span></code>.
      </p>
<div class="blockquote"><blockquote class="blockquote"><p>
          <span class="bold"><strong>Formally:</strong></span> <code class="computeroutput"><span class="identifier">R</span><span class="