Json.Assoc
type ('a, 'b) t = ('a * 'b) list
val yojson_of_t : ('a -> Yojson.Safe.t) -> ('b -> 'c) -> ('a * 'b) list -> [> `Assoc of (string * 'c) list ]
val t_of_yojson : ([> `String of string ] -> 'a) -> (Yojson.Safe.t -> 'b) -> Yojson.Safe.t -> ('a * 'b) list