code: def getClient(self):
          
          client = self.Schema().getField('Client').get(self)
          if client:
              return client
          client = self.aq_parent
          if IClient.providedBy(client):
              return client
docs: Retrieves the Client for which the current Batch is attached to
             Tries to retrieve the Client from the Schema property, but if not
             found, searches for linked ARs and retrieve the Client from the
             first one. If the Batch has no client, returns None.