title: GUID / UUID type in typescript
body: <p>I have this function:</p>
  
  <pre><code>function getProduct(id: string){    
      //return some product 
  }
  </code></pre>
  
  <p>where id is actually GUID. Typescript doesn't have guid type. Is it possible create type <code>GUID</code> manually?</p>
  
  <pre><code>function getProduct(id: GUID){    
      //return some product 
  }
  </code></pre>
  
  <p>so if instead <code>'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'</code> will be some <code>'notGuidbutJustString'</code> then I will see typescript compilation error.</p>
  
  <p><strong>Update:</strong> as David Sherret said: there is no way to ensure a string value based on regex or some other function at compile time but it is possible do all the checks in one place at run time.</p>