Multivariate Bijectors Tutorial issue

[maulberto3]

Issue Description

The Multivariate Bijectors tutorial notebook has an issue: someone hit a keyboard interrupt and so it's not complete.

Steps to Reproduce

No steps to reproduce needed, here's a snapshot stright from this github (https://github.com/facebookincubator/flowtorch/blob/main/tutorials/multivariate_bijections.ipynb)

Expected Behavior

Users should expect the tutorial to be complete.

[stefanwebb]

Thanks for picking up on this! It's an easy fix although with the developments at Meta this morning, I may need to relocate this repo to another place before I can merge PRs