Lifetime

<div class="r2 lifetime" data-step="0"><div class="r2-head">REFERENCE LIFETIME<span class="r2-live"></span></div><div class="r2-stage"><div class="r2-time-head"><span>start</span><span>time →</span><span>end</span></div><div class="r2-time-bar owner">value lives</div><div class="r2-time-bar ref">reference</div><div class="r2-time-bar invalid">invalid extension</div></div><div class="r2-foot"><span class="r2-caption"></span><span class="r2-progress"></span></div></div>

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