Lazy_vector.MutableMake generates a lazy vector module using a given Key module.
module type ImmutableS = Smodule type S = sig ... endS is the signature of a mutable lazy vector module.
module Make
(Vector : ImmutableS) :
S with type key = Vector.key and module Vector = Vectormodule Int32Vector : S with type key = int32 and module Vector = Int32Vectormodule Int64Vector : S with type key = int64 and module Vector = Int64Vector