title: npm: find out which dependencies use a given package (indirectly)
body: <p>I'm currently working on a node.js-project and I've been keeping up with the most recent node releases during development. Now that node 6 is out, I wanted to see if I could make that decision as well.</p>
  
  <p>It turns out some of the modules I use are dependent on older versions of <code>graceful-fs</code> which doesn't support node 6. I get warnings when installing and executing my application, but I can't determine where the <code>graceful-fs</code> package is being used (indirectly).</p>
  
  <p>How can I find out?</p>