def operating_system(os):
    valid_os = ['WINDOWS', 'AMAZON_LINUX', 'AMAZON_LINUX_2', 'UBUNTU', 'REDHAT_ENTERPRISE_LINUX', 'SUSE', 'CENTOS']
    if (os not in valid_os):
        raise ValueError(('OperatingSystem must be one of: "%s"' % ', '.join(valid_os)))
    return os
def operating_system(os):
    valid_os = ['WINDOWS', 'AMAZON_LINUX', 'AMAZON_LINUX_2', 'UBUNTU', 'REDHAT_ENTERPRISE_LINUX', 'SUSE', 'CENTOS']
    if (os not in valid_os):
        raise ValueError(('OperatingSystem must be one of: "%s"' % ', '.join(valid_os)))
    return os