type t = [ | `Replace of (string * string) list| `Extend of (string * string) list| `Override of (string * string option) list| `Replace_raw of string list
]val sexp_of_t : t -> Sexplib0.Sexp.tval t_of_sexp : Sexplib0.Sexp.t -> tval __t_of_sexp__ : Sexplib0.Sexp.t -> t