title: C# How to determine if a type implements a given interface?
body: <p>I want the following to return <code>true</code>:</p>
  
  <pre><code>var isIt = IsDisposable(typeof(TextWriter));
  </code></pre>
  
  <p>where:</p>
  
  <pre><code>bool IsIDisposable(Type t){
      ??? 
      // I tried:
      //return t.IsSubclassOf(typeof(IDisposable)); //returns false
      // the other t.IsXXX methods don't fit the requirement as far as I can tell
  }
  </code></pre>