title: What is a private interface?
body: <p>In an interview a while ago for a .NET position the interviewer asked me "what would you use a private interface for?".</p>
  
  <p>I asked him did he mean the difference between implicit vs explicit interface implementation to which he answered no.</p>
  
  <p>So I'm wondering:</p>
  
  <ol>
  <li>What he meant?</li>
  <li>What you would use a private interface for?</li>
  </ol>