title: Parse YouTube duration ISO 8601
body: <p>How can I parse the youtube duration format which I believe is ISO 8601</p>
  
  <p>This request</p>
  
  <pre><code>https://www.googleapis.com/youtube/v3/videos?id=Kdgt1ZHkvnM&amp;part=contentDetails&amp;key={API_KEY}
  </code></pre>
  
  <p>Returns</p>
  
  <pre><code>{
   "kind": "youtube#videoListResponse",
   "etag": "\"QVyS2yjpsZ-tKkk4JvgYeO_YkzY/Do26Zx0a-KfdN4FPvoMAgqiFNRA\"",
   "pageInfo": {
    "totalResults": 1,
    "resultsPerPage": 1
   },
   "items": [
    {
     "kind": "youtube#video",
     "etag": "\"QVyS2yjpsZ-tKkk4JvgYeO_YkzY/yZ-09PZbpkEHSEcQeekJuGOCbJY\"",
     "id": "Kdgt1ZHkvnM",
     "contentDetails": {
      "duration": "PT20M1S",
      "dimension": "2d",
      "definition": "hd",
      "caption": "false",
      "licensedContent": false
     }
    }
   ]
  }
  </code></pre>
  
  <p>Is there a library that parses this format "<strong>PT20M1S</strong>" for .Net?</p>