code: func (m *TemplateMessage) MarshalJSON() ([]byte, error) {
  	return json.Marshal(&struct {
  		Type       MessageType      `json:"type"`
  		AltText    string           `json:"altText"`
  		Template   Template         `json:"template"`
  		QuickReply *QuickReplyItems `json:"quickReply,omitempty"`
  	}{
  		Type:       MessageTypeTemplate,
  		AltText:    m.AltText,
  		Template:   m.Template,
  		QuickReply: m.quickReplyitems,
  	})
  }
docs: // MarshalJSON method of TemplateMessage