:</p>
<pre><code class="lang-ts"><span class="cm-keyword">class</span> <span class="cm-variable">C</span> {
}
<span class="cm-comment">// ... &#xB2E4;&#xB978; &#xC704;&#xCE58; ...</span>
<span class="cm-variable">namespace</span> <span class="cm-variable">C</span> {
  <span class="cm-keyword">export</span> <span class="cm-keyword">interface</span> <span class="cm-variable">D</span> { }
}
<span class="cm-keyword">let</span> <span class="cm-variable">y</span>: <span class="cm-variable-3">C</span>.<span class=