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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_openstack_release_string(self):
 """Get openstack release string. Return a string representing the openstack release. """

        releases = OrderedDict([
            ('trusty', 'icehouse'),
            ('xenial', 'mitaka'),
            ('yakkety', 'newton'),
            ('zesty', 'ocata'),
            ('artful', 'pike'),
            ('bionic', 'queens'),
            ('cosmic', 'rocky'),
            ('disco', 'stein'),
        ])
        if self.openstack:
            os_origin = self.openstack.split(':')[1]
            return os_origin.split('%s-' % self.series)[1].split('/')[0]
        else:
            return releases[self.series]