You can search for identifiers within the package.
in-package search v0.2.0
type in_file
val open_in : string -> in_file
val read : ?suffix:string -> in_file -> string -> packed_array
val close_in : in_file -> unit
type out_file
val open_out : string -> out_file
val write : ?suffix:string -> out_file -> string -> ('a, 'b, 'c) Stdlib.Bigarray.Genarray.t -> unit
val close_out : out_file -> unit