fix to avoid 'DATA_DIR not found'
Thanks @ekmb , just did :)  yes please, this looks like bugfix for r1.0.0rc1 Thanks @ekmb and @okuchaiev - rebasing to r1.0.0rc1 resulted in many file changes, but notebook hasn't changed at all. This pull request **introduces 4 alerts** when merging f6e7fc182f103e0b58c47ccb39645995ac178324 into bc38019ffa144dcf0bfc735a9838bb0e6fba71ab - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-2d6425e234837de89ff7012c4a2fb38315c3ad09)

**new alerts:**

* 4 for Unused import
Signed-off-by: Hoo Chang Shin <hshin@nvidia.com>