type ('a, 'b) t
val to_json : 'a to_json -> 'b to_json -> ('a, 'b) t to_json
val of_json : 'a of_json -> 'b of_json -> ('a, 'b) t of_json
val compare : 'a compare -> 'b compare -> ('a, 'b) t compare
val bin_size_t : ('a, 'b, ('a, 'b) t) Bin_prot.Size.sizer2
val bin_write_t : ('a, 'b, ('a, 'b) t) Bin_prot.Write.writer2
val bin_read_t : ('a, 'b, ('a, 'b) t) Bin_prot.Read.reader2