code: def _get_override_lookup_session(self):
          
          from ..utilities import OVERRIDE_VAULT_TYPE
          try:
              override_vaults = self._get_vault_lookup_session().get_vaults_by_genus_type(OVERRIDE_VAULT_TYPE)
          except Unimplemented:
              return None
          if override_vaults.available():
              vault = override_vaults.next()
          else:
              return None
          session = self._get_authz_manager().get_authorization_lookup_session_for_vault(vault.get_id())
          session.use_isolated_vault_view()
          return session
docs: Gets the AuthorizationLookupSession for the override typed Vault
  
          Assumes only one