def get_short_id_from_ec2_arn(arn: str) -> str:
    """
    Return the short-form resource ID from an EC2 ARN.
    For example, for "arn:aws:ec2:us-east-1:test_account:instance/i-1337", return 'i-1337'.
    :param arn: The ARN
    :return: The resource ID
    """
    return arn.split('/')[-1]