fix argmax and batch deprecations

src/utils.jl

@@ -24,7 +24,7 @@ julia> chunk(1:10, 3)
 """
 chunk(xs, n) = collect(Iterators.partition(xs, ceil(Int, length(xs)/n)))
 
-batchindex(xs, i) = (reverse(Base.tail(reverse(indices(xs))))..., i)
+batchindex(xs, i) = (reverse(Base.tail(reverse(axes(xs))))..., i)
 
 """
     frequencies(xs)

test/utils.jl

@@ -90,3 +90,9 @@ end
   m = RNN(10, 5)
   @test size.(params(m)) == [(5, 10), (5, 5), (5,), (5,)]
 end
+
+@testset "batch" begin
+  xs = [[1,2,3],[4,5,6]]
+  X =  [1 4; 2 5; 3 6]
+  @test batch(xs) == X
+end