anchor.diff:              resp.DesignDocs <- Seq.ofList designDocs
               resp
   
  -        member __.GetAsync(id: string, ?rev: string): Task<'doctype> =
  +        member __.GetAsync(id: string, [<Optional; DefaultParameterValue(null)>] ?rev: string): Task<'doctype> =
               client 
               |> get id rev
               |> Async.Map toDoc
               |> task
   
  -        member __.FindByExpressionAsync (exp, ?options): Task<IEnumerable<'doctype>> = 
  +        member __.FindByExpressionAsync (exp, [<Optional; DefaultParameterValue(null)>] ?options): Task<IEnumerable<'doctype>> = 
               let opts = 
                   options 
                   |> Option.map findOptionsToFs 
  
positive.code:             |> count 
              |> task
  
          member __.CountByExpressionAsync (exp): Task<int> = 
              exp 
              |> ExpressionParser.parse 
              |> countBySelector 
  
negative.code:     open System.Threading.Tasks
      open System.Collections.Generic
      open Davenport.Csharp.Types
      open System.Runtime.InteropServices
  
      module ExpressionParser = 
          open System.Linq.Expressions
  