Rust async closures

<div class="v"><header><b>ASYNC CLOSURE BORROW</b><span id="state"></span></header><main><div class="life"><div class="capture">CAPTURE <b>vec</b></div><div class="future" id="future">FUTURE <b>await</b></div><div class="line" id="line"></div></div><div class="borrow" id="borrow"></div></main><footer>the returned future may borrow captures</footer></div>

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let n=0;const labels=["capture → future","borrow survives await","future done → borrow ends"];function draw(){document.getElementById("borrow").textContent=labels[n];document.getElementById("future").style.borderColor=n===2?"var(--line)":"var(--accent)";document.getElementById("line").style.opacity=n===2?".2":"1";document.getElementById("state").textContent="phase "+(n+1);n=(n+1)%3}draw();setInterval(draw,1150)