Is there a way to stack JaggedArrays without fromiter()?

Question

I have two 2D JaggedArrays of the same length (in axis=0) that I'd like to stack in axis=1. For example:

a = awkward.fromiter([[0], [3, 4]])
b = awkward.fromiter([[1, 2], [5]])

and I want to get this JaggedArray:

[ [ [0],    [1, 2] ],
  [ [3, 4], [5]    ]  ]

I can get exactly this with the following:

awkward.fromiter(np.stack([a, b], axis=1))

but is there a way to accomplish this directly in awkward, without having to use fromiter() on nested numpy arrays?