--- /dev/null
+type t = string
+type level = int
+val is_logger : t -> bool
+val is_active : t -> bool
+val level : t -> level
+val activate : t -> level -> unit
+val deactivate : t -> unit
+val set_output : Format.formatter -> unit
+val log : t -> level -> string -> unit
+
+val available : unit -> string list