Transformer-VAE (flax) (WIP)

A Transformer-VAE made using flax.

Done as part of Huggingface community training (see forum post).

Builds on T5, using an autoencoder to convert it into an MMD-VAE.

ToDo

[ ] Basic training script working. (Fraser + Theo)
[ ] Add MMD loss (Theo)
[ ] Save a wikipedia sentences dataset to Huggingface (see original https://github.com/ChunyuanLI/Optimus/blob/master/data/download_datasets.md) (Mina)
[ ] Make a tokenizer using the OPTIMUS tokenized dataset.
[ ] Train on the OPTIMUS wikipedia sentences dataset.
[ ] Make Huggingface widget interpolating sentences! (???) https://github.com/huggingface/transformers/tree/master/examples/research_projects/jax-projects#how-to-build-a-demo

Optional ToDos:

[ ] Add Funnel transformer encoder to FLAX (don't need weights).
[ ] Train a Funnel-encoder + T5-decoder transformer VAE.
[ ] Additional datasets:
[ ] Poetry (https://www.gwern.net/GPT-2#data-the-project-gutenberg-poetry-corpus)
[ ] 8-bit music (https://github.com/chrisdonahue/LakhNES)

Follow all steps to install dependencies from https://cloud.google.com/tpu/docs/jax-quickstart-tpu-vm