code: def get_hlu(self, resource, cg_member=None):
          
          host_lun = self.get_host_lun(resource, cg_member=cg_member)
          return host_lun if host_lun is None else host_lun.hlu
docs: Gets the hlu number of a lun, lun snap, cg snap or a member snap of
          cg snap.
  
          :param resource: can be lun, lun snap, cg snap or a member snap of cg
              snap.
          :param cg_member: the member lun of cg if `lun_or_snap` is cg snap.
          :return: the hlu number.