anchor.diff:                  |> Seq.map getMemberByLocation
                   |> Async.Parallel
               return symbolUses |> Seq.choose (Option.bind formatMemberSignature)
  +                              |> Seq.concat
                                 |> Set.ofSeq
           }
   
  
positive.code:             Debug.Assert(symbolUse.Symbol :? FSharpMemberFunctionOrValue, "Only accept symbol use of members.")
              try
                  let m = symbolUse.Symbol :?> FSharpMemberFunctionOrValue
                  let typ = m.FullType
                  let signature = sprintf "%s:%s" m.DisplayName (typ.Format(displayContext))
                  Some (signature.Replace(" ", ""))
              with _ ->
                  None
          async {
  
negative.code:             |> Seq.filter (fun (m, insts) -> 
                  // FullType might throw exceptions due to bugs in FCS
                  try
                      let (TypeOfMember typ) = m 
                      let signature = removeWhitespace (sprintf "%s:%s" m.DisplayName (formatType { ctx with ArgInstantiations = insts }  typ))
                      not (Set.contains signature excludedMemberSignatures) 
                  with _ -> true)
          // All members are already implemented
          if Seq.isEmpty missingMembers then
  