Cannot run gpu modules

Hello,

I am trying out the GPU implementation of the sinkhorn transport, but with not much success.

>>> a=[.5,.5]
>>> b=[.5,.5]
>>> M=[[0.,1.],[1.,0.]]
>>> ot.gpu.sinkhorn(a,b,M,1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: module 'ot' has no attribute 'gpu'

However, the ot.sinkhorn(a,b,M,1) works as expected.
I have cupy installed as well as the CUDA SDK.

Could someone help?