title: How do i make Intersection type optional in typescript
body: <pre><code>interface TypeA {
    a: string
    b: string
  }
  
  interface TypeB {
    c: string
  }
  </code></pre>
  <p>now i want to make a TypeC, a and b is optional, c is required.</p>
  <pre><code>interface TypeC {
    a?: string
    b?: string
    c: string
  }
  </code></pre>
  <p>are there any shortcut to make this?  for example:</p>
  <pre><code>// type TypeC = TypeA? &amp; TypeB
  </code></pre>
  <p>I think it's useful when TypeA is huge</p>