title: Check if Key Exists in NameValueCollection
body: <p>Is there a quick and simple way to check if a key exists in a NameValueCollection without looping through it?</p>
  
  <p>Looking for something like Dictionary.ContainsKey() or similar.</p>
  
  <p>There are many ways to solve this of course. Just wondering if someone can help scratch my brain itch.</p>