Variable length array

I'm creating a backend to use transparently pytables, h5py and h5pyd. I ran my test suite on h5pyd and am confronted with the issue of the variable length array. In h5py, they manage to do it using a "special" dtype: `h5py.string_dtype` or `h5py.vlen_dtype` . After some digging in I found in h5pyd, the function `special_dtype` where the docstring seems promising:
```
vlen = basetype
Base type for HDF5 variable-length datatype. This can be Python
str type or instance of np.dtype.
Example: special_dtype( vlen=str )
```
however after trying it out it seems its working only in the case where `vlen=str` and not any numpy dtype. Using a special dtype of np.uint32s I could create a dataset but when trying to access a given element I got this traceback:
`File "", line 1, in
dset[0]
File "C:\Miniconda3\envs\pymodaq_dev\lib\site-packages\h5pyd\_hl\dataset.py", line 802, in __getitem__
arr1d = bytesToArray(rsp, mtype, page_mshape)
File "C:\Miniconda3\envs\pymodaq_dev\lib\site-packages\h5pyd\_hl\base.py", line 503, in bytesToArray
offset = readElement(data, offset, arr, index, dt)
File "C:\Miniconda3\envs\pymodaq_dev\lib\site-packages\h5pyd\_hl\base.py", line 467, in readElement
arr[index] = vlen(0)
TypeError: 'numpy.dtype' object is not callable`

Then a bit further in the code I found :

> def check_dtype(**kwds):
> """ Check a dtype for h5py special type "hint" information. Only one
> keyword may be given.
>
> vlen = dtype
> If the dtype represents an HDF5 vlen, returns the Python base class.
> Currently only builting string vlens (str) are supported. Returns
> None if the dtype does not represent an HDF5 vlen.

So the question is: is it or will it be possible to use any numpy dtype for variable length arrays in h5pyd?

Thx