Sourcetype t = (string * string) list Sourceval mem : (string * 'a) list -> string -> bool Sourceval add_unless_exists :
(string * 'a) list ->
string ->
'a ->
(string * 'a) list Sourceval get : (string * string) list -> string -> string option Sourceval rem : (string * 'a) list -> string -> (string * 'a) list