title: How do you get `npm prune --production` to operate recursively?
body: <p>Seems like a fairly straightforward thing, but I can't find anything on the interwebs.</p>
  <p>It appears that <code>npm prune --production</code> only descends into the current package's <code>node_modules</code> folder.  However, it does <em>not</em> recurse down the <code>node_modules</code> tree to remove <code>devDependencies</code> recursively.  The result is that my project is a bit smaller in size thanks to the removal of its <em>direct</em> <code>devDependencies</code>, but the <code>devDependencies</code> of the project remain transitively, leaving it unnecessarily large in real projects.</p>
  <p>Behavior is identical from <code>npm</code> versions <code>6.4.1</code> through <code>6.14.4</code>.</p>