open Types

let rec filter instream snos =
  if snos = [] then [< >] else
  match instream with parser
    | [< 'page ; rest >] 
             -> if List.exists (fun a -> a = page.serialno) snos then
                  begin
                    let snos2 = 
                      if page.eos then 
                        List.filter (fun a -> a != page.serialno) snos
                      else
                        snos in
                      [< 'page ; filter rest snos2 >]
                  end
                else [< filter rest snos >]
    | [< >]              -> [< >]