I tried this:
page.find("#parentNode").first(".childClass").click
but got the error: NoMethodError:undefined method 'click' for nil:NilClass
How can I click childNode1 or childNode2
<div id="parentNode">
     <div id="childNode1" class="childClass">
         <img src="path img1"></img>
     </div>
     <div id="childNode2" class="childClass">
        <img src="path img2"></img>
     </div>
 </div>