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 ifprintf : 'a -> ('b, 'a, unit) Pervasives.format -> 'b
val kfprintf :
(Pervasives.out_channel -> 'a) ->
Pervasives.out_channel ->
('b, Pervasives.out_channel, unit, 'a) Pervasives.format4 -> 'b
val ikfprintf :
(Pervasives.out_channel -> 'a) ->
Pervasives.out_channel ->
('b, Pervasives.out_channel, unit, 'a) Pervasives.format4 -> 'b
val ksprintf :
(string -> 'a) -> ('b, unit, string, 'a) Pervasives.format4 -> 'b
val kbprintf :
(Buffer.t -> 'a) ->
Buffer.t -> ('b, Buffer.t, unit, 'a) Pervasives.format4 -> 'b
val kprintf :
(string -> 'a) -> ('b, unit, string, 'a) Pervasives.format4 -> 'b
end`