code: def addcomment(self, creditmemo_increment_id,
              comment, email=True, include_in_email=False):
          
          return bool(
              self.call(
                  'sales_order_creditmemo.addComment',
                  [creditmemo_increment_id, comment, email, include_in_email]
              )
          )
docs: Add new comment to credit memo
  
          :param creditmemo_increment_id: Credit memo increment ID
  
          :return: bool