Fork the repository by
   clicking on the Fork button on the repository's page. This creates a copy of the code
   under your GitHub user account.

Clone your fork to your local disk, and add the base repository as a remote:

   git clone git@github.com:<your Github handle>/transformers.git
   cd transformers
   git remote add upstream https://github.com/huggingface/transformers.git

Create a new branch to hold your development changes: