type dest = {uri:Uri.t;
             auth_hdrs:Cohttp.Header.t}


let fetch des =
  let open Lwt in
  try
    Cohttp_lwt_unix.Client.call ~headers:des.auth_hdrs `GET des.uri >>=
      fun (resp, body) ->
      Cohttp_lwt_body.to_string body >>= fun b ->
      Lwt_io.printl b
  with _ ->
    Lwt.return (print_endline "some exception")