"block" until the operation completes.</span>
        <span class="comment">// It isn't really blocking. Instead, the fiber implementation saves</span>
        <span class="comment">// the call stack and suspends the function until the asynchronous</span>
        <span class="comment">// operation is complete. Then it restores the call stack, and resumes</span>
        <span class="comment">// the function to the statement following the async_resolve. This</span>
        <span class="comment">// allows an a