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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def operating_system():
 """Return a string identifying the operating system the application is running on. :rtype: str """

    if platform.system() == 'Darwin':
        return 'OS X Version %s' % platform.mac_ver()[0]
    distribution = ' '.join(platform.linux_distribution()).strip()
    os_platform = platform.platform(True, True)
    if distribution:
        os_platform += ' (%s)' % distribution
    return os_platform