title: Taking an existing type and making each of its properties optional
body: <p>Can I pick a some properties from a type while setting them to <code>Optional</code> in the new type?</p>
  
  <p>Existing type:</p>
  
  <pre class="lang-js prettyprint-override"><code>interface RequiredInfo {
      name: string
      ...
  }
  </code></pre>
  
  <p>Desired mapped type:</p>
  
  <pre><code>type OptionalInfo = { 
      name?: string
      ...
  }
  </code></pre>