docs: def _check_iscsi_rest_patch_allowed(self):
          """Checks if patch is supported on iscsi.
  
          :returns: iscsi url.
          :raises: IloError, on an error from iLO.
          :raises: IloCommandNotSupportedError, if the command is not supported
                   on the server.
          """
  
          headers, bios_uri, bios_settings = self._check_bios_resource()
          # Check if the bios resource exists.
  
          if('links' in bios_settings and 'iScsi' in bios_settings['links']):
              iscsi_uri = bios_settings['links']['iScsi']['href']
              status, headers, settings = self._rest_get(iscsi_uri)
  
              if status != 200:
                  msg = self._get_extended_error(settings)
                  raise exception.IloError(msg)
  
              if not self._operation_allowed(headers, 'PATCH'):
                  headers, iscsi_uri, settings = (
                      self._get_iscsi_settings_resource(settings))
                  self._validate_if_patch_supported(headers, iscsi_uri)
  
              return iscsi_uri
  
          else:
              msg = ('"links/iScsi" section in bios'
                     ' does not exist')
              raise exception.IloCommandNotSupportedError(msg)