title: Add a peramater to type alias
body: <p>I am using a function from a library whose type is </p>
  
  <pre><code>type QueryFetcher = (query: string, variables?: Record&lt;string, any&gt;) =&gt; Promise&lt;QueryResponse&gt; | QueryResponse;
  </code></pre>
  
  <p>and I would like to add a an additional argument to this type with out editing the type declaration in the source file.</p>
  
  <p>I thought I could do something like</p>
  
  <pre><code>type WithHeader = (header: string) =&gt; Promise&lt;QueryResponse&gt; | QueryResponse
  
  type QueryFetcherWithHeader = QueryFetcher &amp; WithHeader
  
  </code></pre>
  
  <p>and that would yield </p>
  
  <pre><code>(query: string, variables?: Record&lt;string, any&gt;, header: string) =&gt; Promise&lt;QueryResponse&gt; | QueryResponse;
  </code></pre>
  
  <p>But it doesn't</p>
  
  <p>Obviously, I dont understand something here, but I cant find something </p>