1. Open an open pull request on GitHub which normally has the following format:
  2. Open a terminal for running a git command (e.g. bash, cmd, powershell, etc...).
  3. Navigate to the location where your git forked repository was cloned.
  4. Download a copy of a pull request using the following command: 
    git fetch upstream pull/<ID>/head:<NEW BRANCH>

    Where the variables can be describe as the following:

    <ID> This is the associated code attached to the pull request. Normally has the following format #<ID> (e.g. #123) or see the format from step 1.
    <NEW BRANCH> This is the unique desired branch name on your fork.
  5. Switch to the new branch and do what you want (e.g. code review, testing) using the following command: 
    git checkout <NEW BRANCH>