You can search for identifiers within the package.
in-package search v0.2.0
type t =
| Buffer of Buffer.t
| Out_channel of out_channel
val output_buffer : t -> Buffer.t -> unit
val flush : t -> unit
val output_string : t -> string -> unit
val output_char : t -> char -> unit
val printf : t -> ('a, Buffer.t, unit) format -> 'b
val output_charstream : t -> Mpp_charstream.charstream -> unit
val cat : t -> string -> unit