Make1_generic is for blitting between two values of the same container type that's not fully polymorphic (in the sense of Container.Generic).
Make1_generic
Sequence : Sequence1
type 'a t
val blit : ('a t, 'a t) blit
val blito : ('a t, 'a t) blito
val unsafe_blit : ('a t, 'a t) blit
val sub : ('a t, 'a t) sub
val subo : ('a t, 'a t) subo