code: def _get_openstack_release_string(self):
          
          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]
docs: Get openstack release string.
  
             Return a string representing the openstack release.