title: Set the default value of an optional 'List(Of t)' parameter to an empty list?
body: <p>In this example, I can't figure out how to set the optional parameter <code>c</code> to an empty <code>List(Of thing)</code>:</p>
  
  <pre><code>Sub abcd(a as something, b as something, optional c as List(Of thing) = ?? )
      ' *stuff*
  End Sub
  </code></pre>
  
  <p>I considered setting <code>c</code> to <code>null</code>, but that seems like a bad thing to do.</p>