docs: def get_vault_admin_session(self):
          """Gets the OsidSession associated with the vault administration service.
  
          return: (osid.authorization.VaultAdminSession) - a
                  ``VaultAdminSession``
          raise:  OperationFailed - unable to complete request
          raise:  Unimplemented - ``supports_vault_admin() is false``
          *compliance: optional -- This method must be implemented if
          ``supports_vault_admin()`` is true.*
  
          """
          if not self.supports_vault_admin():
              raise errors.Unimplemented()
          # pylint: disable=no-member
          return sessions.VaultAdminSession(runtime=self._runtime)