optionally accept specially labelled children that will appear in named "slots".
<!-- load web component module --><scripttype="module"src="components/search-box.js"><!-- use its tag inHTML--><search-boxplaceholder="Search..."></search-box><!--usingnamed slots --><search-box> <imgsrc="images/search-icon.png"slot="left"/> <imgsrc="images/cancel-icon.png"slot="right"/></search-box>