Printf

`sig
val fprintf :
Pervasives.out_channel ->
('a, Pervasives.out_channel, unit) Pervasives.format -> 'a
val printf : ('a, Pervasives.out_channel, unit) Pervasives.format -> 'a
val eprintf : ('a, Pervasives.out_channel, unit) Pervasives.format -> 'a
val sprintf : ('a, unit, string) Pervasives.format -> 'a
val bprintf : Buffer.t -> ('a, Buffer.t, unit) Pervasives.format -> 'a
val kprintf : (string -> 'a) -> ('b, unit, string, 'a) format4 -> 'b
val scan_format :
string ->
int ->
(string -> int -> 'a) ->
('b -> 'c -> int -> 'a) -> ('d -> int -> 'a) -> (int -> 'a) -> 'a
end`