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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 _get_package_manager(self):
        '''
        Get package manager.

        :return:
        '''
        ret = None
        if self.__grains__.get('os_family') in ('Kali', 'Debian'):
            ret = 'apt-get'
        elif self.__grains__.get('os_family', '') == 'Suse':
            ret = 'zypper'
        elif self.__grains__.get('os_family', '') == 'redhat':
            ret = 'yum'

        if ret is None:
            raise InspectorKiwiProcessorException('Unsupported platform: {0}'.format(self.__grains__.get('os_family')))

        return ret