title: get all elements by class name in polymer
body: <p>Can someone please tell me how to get all elements by class name in polymer? We can surely is <code>this.$$(selector)</code>, but in the <a href="https://www.polymer-project.org/1.0/docs/devguide/local-dom" rel="nofollow noreferrer">documentation</a> it is clearly mentioned that <code>$$ returns the first node in the local DOM that matches selector</code>.</p>
  
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