title: Rollup, VueJS, install Vue Portal
body: <p>How can I install an external package in <code>Rollup</code> in VueJS. I'm trying to install VuePortal, but I need to use <code>Vue.use(PortalVue)</code>, but I don't where put it.</p>
  <p>I tried with a package called <code>rollup-plugin-auto-external</code>, and I put it in:</p>
  <pre><code>plugins: [
          ...
          autoExternal(),
          ...
      ],
  </code></pre>
  <p>Also I put into the <code>externals</code>'s object, but nothing.</p>
  <p>Thanks</p>