let rec isInListN x n=
  match n with
  |[]-> false
  |e::n' -> (match e with
             | AssignArg(x,_) ->true
             | _-> isInListN x n'
            )


let rec isInListN x n=
  match n with
  |[]-> false
  |e::n' -> (match e with
             | AssignArg(z,_) when z=x->true
             | _-> isInListN x n'
            )