anchor.diff:      match opt with 
       | Some v -> Nullable v
       | _ -> Nullable()
  -    +    
  
positive.code:   static member AsOption str =
      if String.IsNullOrWhiteSpace str then None else Some str
  
    /// Parse date time using either MS JSON format or using ISO 8601
    /// that is, either "Date(<msec-since-1/1/1970>)" or something
    /// along the lines of "2013-01-28T00:37Z"
    static member AsDateTime culture (text:string) =
      // Try parse "Date(<msec>)" style format
  
negative.code: #else
      RegexOptions.Compiled
  #endif
    // note on the regex we have /Date()/ and not \/Date()\/ because the \/ escaping 
    // is already taken care of before AsDateTime is called
    let msDateRegex = lazy (new Regex(@"^/Date\((-?\d+)(?:-\d+)?\)/$", regexOptions))
  
  type Operations = 
  