CuIterator assumes batches to consist of multiple arrays

[maleadt]

When batching over a single array, stuff goes wrong:

julia> a = CuArrays.ones(10)
10-element CuArray{Float32,1,Nothing}:
 1.0
 1.0
 1.0
 1.0
 1.0
 1.0
 1.0
 1.0
 1.0
 1.0

julia> for (i, batch) in enumerate(CuIterator(Iterators.partition(a, 5)))
       @show i batch
       end
i = 1
batch = Float32[1.0, 1.0, 1.0, 1.0, 1.0]
ERROR: MethodError: no method matching unsafe_free!(::Float32)

The docs should probably also use Iterators.partition, it's a nice way of expressing this.

[maleadt]

Workaround:

julia> for (i, (batch,)) in enumerate(CuIterator(map(tuple, Iterators.partition(a, 5))))
       @show i batch
       end
i = 1
batch = Float32[1.0, 1.0, 1.0, 1.0, 1.0]
i = 2
batch = Float32[1.0, 1.0, 1.0, 1.0, 1.0]

[maleadt]

This works now.