title: How to create Set Extension to find unique object in the set with property?
body: <p>Have looked at a couple of solutions to find the first element in an Array where the field in a struct matches, here:
  <a href="https://stackoverflow.com/questions/26073331/find-object-with-property-in-array">Find object with property in array</a> and here: <a href="https://stackoverflow.com/questions/28727845/find-an-object-in-array">find object in array</a></p>
  
  <p>Adapted to only return a match if a single unique match:</p>
  
  <pre><code>    var foundAction: SequenceAction?
      let filteredActions = currentStatus.seqActionsList.filter({$0.verb == actionCommand})
      if filteredActions.count == 1
      {
          foundAction = filteredActions.first
      }
  </code></pre>
  
  <p>Keep using this snippet but cannot figure how to add as an extension to Set?</p>