rface you need to implement, HttpClientImpl.</p>
<div class="codehilite"><pre><span></span><span class="kr">export</span> <span class="kr">interface</span> <span class="nx">HttpClientImpl</span> <span class="p">{</span>
    <span class="nx">fetch</span><span class="p">(</span><span class="nx">url</span>: <span class="kt">string</span><span class="p">,</span> <span class="nx">options</span>: <span class="kt">FetchOptions</span><span class="p">)</span><span class="o">:</span> <span class="nx">Promise</span><s