You can search for identifiers within the package.
in-package search v0.2.0
module IO : sig ... end
type path
val exists : path -> bool IO.t
val kind : path -> [ `Regular_file | `Directory | `Other ] IO.t
val read : path -> string list IO.t
val concat : path -> string -> path
val response_document : ?mime:mime -> path -> response IO.t
val pp_io_err : Stdlib.Format.formatter -> exn -> unit