title: How to overwrite channel permissions with bitfield
body: <p>I tried to get my bot to save channel permissions but it only saves its bitfield. Can I somehow overwrite channel permissions for a specific role only using the bitfield?</p>
  
  <p>I tried doing something like this:</p>
  
  <pre class="lang-js prettyprint-override"><code>channel.overwritePermissions(role, {
    permissions: perms
  });
  </code></pre>
  
  <p>and then tried changing it to:</p>
  
  <pre class="lang-js prettyprint-override"><code>channel.overwritePermissions(role, {
    bitfield: perms
  });
  </code></pre>
  
  <p>It just puts <code>/</code> for every permission.</p>