anchor.diff:  let parseAddArgumentArguments (args : string list) =
       match List.length args with
           | 0 | 1 | 2 -> raise (ArgumentException "Too few arguments")
  -        | 3 -> (parsePos args.[0], args.[1], args.[2], None)
  -        | 4 -> (parsePos args.[0], args.[1], args.[2], Some args.[3])
  +        | 3 -> (parsePosition args.[0], args.[1], args.[2], None)
  +        | 4 -> (parsePosition args.[0], args.[1], args.[2], Some args.[3])
           | _ -> raise (ArgumentException "Too many arguments")
   
   let filenameAndActionFromArguments args =
  
positive.code: 
  let AddArgument filename position argumentName defaultValue =
      let source = getSource filename
      let tree = (Ast.Parse source).Value
      let bindingRange = DefaultBindingRange source tree position
      if Option.isSome bindingRange then
          DoAddArgument source tree bindingRange.Value argumentName defaultValue
      else
          raise (ArgumentException "No binding found around the given position")
  
  let printUsage () =
      printfn "Usage:"
  
negative.code: open FSharpRefactor.Engine.Refactoring
  open FSharpRefactor.Refactorings
  open FSharpRefactor.Refactorings.ExtractFunction
  
  exception ArgumentException of string
  
  