title: `part:` modifier in node import statement
body: <p>I came across this code in a javascript / Node project but can't find any explanation online as to what it is and how it works.</p>
  <pre class="lang-js prettyprint-override"><code>import PatchEvent, {set, unset} from 'part:@sanity/form-builder/patch-event';
  </code></pre>