def METHOD_NAME(self):
    cmdline = self.prefix
    cmdline += '--instance-id i-1234 '
    # Can't mix non-value + value version of the arg.
    cmdline += '--no-ebs-optimized '
    cmdline += '--ebs-optimized '
    self.assert_params_for_cmd(cmdline, expected_rc=255,
                                stderr_contains='Cannot specify both')