code: def serialize(self):
          
  
          if self.response is not None:
              return {'messaging_type': 'RESPONSE'}
  
          if self.update is not None:
              return {'messaging_type': 'UPDATE'}
  
          if self.tag is not None:
              return {
                  'messaging_type': 'MESSAGE_TAG',
                  'tag': self.tag.value,
              }
  
          if self.subscription is not None:
              return {'messaging_type': 'NON_PROMOTIONAL_SUBSCRIPTION'}
docs: Generates the messaging-type-related part of the message dictionary.