class="punctuation">.</span><span class="function"><a href="/api/checkpoints/interfaces/checkpoints/checkpoints/methods/setter/addcheckpoint/">addCheckpoint</a></span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
<span class="comment">// -> [['0'], '3', []]</span>
<span class="comment">// Previous redo of checkpoints '1' and '2' are now not possible.</span>

checkpoints<span class="punctuation">.</span><span class="function"><a href="/api/checkpoints/