anchor.diff:  
       let starlingR =
           match (requestFromStage opts.stage) with
  +        // Handle pseudo-requests here, as it's cleaner than doing so in
  +        // runStarling.
  +        | Some Request.List ->
  +            ok (Response.List (Map.map (fun _ -> fst) requestMap))
           | Some otype -> runStarling times optS backendS verbose otype opts.input
           | None -> fail Error.BadStage
   
  
positive.code: /// Pretty-prints a response.
  let printResponse mview =
      function
      | Frontend f -> Lang.Frontend.printResponse mview f
      | GraphOptimise g ->
          printUVModelView printGraph mview g
  
negative.code: 
  /// Enumeration of possible requests to Starling.
  type Request =
      /// List all available requests.
      | List
      /// Run the language frontend only, with the given request.
      | Frontend of Lang.Frontend.Request
      /// Stop at graph optimisation.
  