Output_method.FormatA format specifies how the user wants their captured results to be formatted by providing a sexp structure in which the captures will get embedded.
include Sexplib0.Sexpable.S with type t := tinclude Sexplib0.Sexpable.Of_sexp with type t := tval t_of_sexp : Sexplib0.Sexp.t -> tinclude Sexplib0.Sexpable.Sexp_of with type t := tval sexp_of_t : t -> Sexplib0.Sexp.tval ts_of_string : string -> t listval all_captures : t -> string listval embed_captures : t -> f:(string -> Core.Sexp.t list) -> Core.Sexp.t list