def validate_args(args):
    """Validate command-line arguments."""
    if not any([args.environment, args.stage, args.account]):
        sys.exit(NO_ACCT_OR_ENV_ERROR)
    if args.environment and args.account:
        sys.exit(ENV_AND_ACCT_ERROR)
    if args.environment and args.role:
        sys.exit(ENV_AND_ROLE_ERROR)
Validate command-line arguments.