title: How to select multiple selectors with selectAll?
body: <p>Is it possible to select multiple selectors in D3 using <code>selectAll</code>? </p>
  
  <p>I want something like <code>svg.selectAll("class1", "circle", "id2")</code> to select all <code>circle</code> elements, <code>class1</code> elements and <code>id2</code> elements.</p>
  
  <p>Is this possible?</p>