title: Can custom headers be set for urql?
body: <p>The Github GraphQL v4 API has so-called <a href="https://developer.github.com/v4/previews" rel="nofollow noreferrer">Schema Previews</a> where you can use new schema features - but it requires a custom <code>Accept</code> header.</p>
  
  <p>I've used the Apollo client before but I'd like to try this new app with Formidables <em>urlq</em>. Is there a way to set customer headers with the urql client?</p>
  
  <p><strong>Update</strong></p>
  
  <p>I think this has gone into the codebase, it's just not documented - <a href="https://github.com/FormidableLabs/urql/pull/96/files" rel="nofollow noreferrer">https://github.com/FormidableLabs/urql/pull/96/files</a></p>