title: How to use out attributes in an F# Interface?
body: <p>I would like to define one of my parameters to be a C# out parameter in one of my interfaces.  I realize that F# supports <code>byref</code> but how can I apply the <code>System.Runtime.InteropServices.OutAttribute</code> to one of my interface parameters?</p>
  
  <p>C# Interface I am trying to replicate</p>
  
  <pre><code>public interface IStatisticalTests
  {
      void JohansenWrapper(
          double[,] dat,
          double alpha,
          bool doAdfPreTests,
          out double cointStatus,
          out JohansenModelParameters[] johansenModelParameters);
  }
  </code></pre>