sig
exception Migration_forbidden
val safe_read : Unix.file_descr -> String.t -> int -> unit
val safe_write : Unix.file_descr -> String.t -> int -> unit
val read_line : unit -> String.t
val create : (int -> unit) -> int -> unit
val computer : int Pervasives.ref
val nbr_comp : int Pervasives.ref
val last_comp : int Pervasives.ref
val migrate : int -> unit
val exit : unit -> unit
end