title: Nito.AsyncEx + .Net-4.0 = 'AsyncContext' does not exist in the namespace 'Nito.AsyncEx'
body: <p>I need to run Nito.AsyncEx with library targeting .Net-4.0. I'm trying the following simple code:</p>
  
  <pre><code>using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Text;
  using System.Threading.Tasks;
  
  namespace TempNet40
  {
      class Program
      {
          static void Main(string[] args)
          {
              Nito.AsyncEx.AsyncContext.Run(() =&gt; MainAsync(args));
          }
  
          static async void MainAsync(string[] args)
          {
  
          }
      }
  }
  </code></pre>
  
  <p>While the above compiles when my lib targets .Net-4.5 or higher - it fails for .Net-4.0 with error:</p>
  
  <blockquote>
    <p>The type or namespace name 'AsyncContext' does not exist in the
    namespace 'Nito.AsyncEx' (are you missing an assembly reference?)</p>
  </blockquote>
  
  <p>Nito.AsyncEx (as well as its .Net-4.0 dependency: Microsoft.Bcl.Async) was installed using NuGet - I guess for .Net-4.0, I need to reference another library... does anybody know which one?</p>