code: def checkout_deploy_branch(deploy_branch, canpush=True):
      
      # Create an empty branch with .nojekyll if it doesn't already exist
      create_deploy_branch(deploy_branch, push=canpush)
      remote_branch = "doctr_remote/{}".format(deploy_branch)
      print("Checking out doctr working branch tracking", remote_branch)
      clear_working_branch()
      # If gh-pages doesn't exist the above create_deploy_branch() will create
      # it we can push, but if we can't, it won't and the --track would fail.
      if run(['git', 'rev-parse', '--verify', remote_branch], exit=False) == 0:
          extra_args = ['--track', remote_branch]
      else:
          extra_args = []
      run(['git', 'checkout', '-b', DOCTR_WORKING_BRANCH] + extra_args)
      print("Done")
  
      return canpush
docs: Checkout the deploy branch, creating it if it doesn't exist.