type 'a t
val blit : ('a t, 'a t) Base.Blit_intf.blit
val blito : ('a t, 'a t) Base.Blit_intf.blito
val unsafe_blit : ('a t, 'a t) Base.Blit_intf.blit
val sub : ('a t, 'a t) Base.Blit_intf.sub
val subo : ('a t, 'a t) Base.Blit_intf.subo