<div class="parent">
<div class="child1"></div>
<div class="child2"></div>
</div>
<div class="parent">
<div class="child1"></div>
<div class="child2"></div>
</div>
<div class="parent">
<div class="child1"></div>
<div class="child2"></div>
</div>
<div class="parent">
<div class="child1"></div>
<div class="child2"></div>
</div>
what's the right solution to swap the order of child1 and child2?