code: def key_pair(i, region):
      
      if i == 0:
          return ("{}_{}".format(RAY, region),
                  os.path.expanduser("~/.ssh/{}_{}.pem".format(RAY, region)))
      return ("{}_{}_{}".format(RAY, i, region),
              os.path.expanduser("~/.ssh/{}_{}_{}.pem".format(RAY, i, region)))
docs: Returns the ith default (aws_key_pair_name, key_pair_path).