code: func (m *Message) IsService() bool {
  	fact := false
  
  	fact = fact || m.UserJoined != nil
  	fact = fact || len(m.UsersJoined) > 0
  	fact = fact || m.UserLeft != nil
  	fact = fact || m.NewGroupTitle != ""
  	fact = fact || m.NewGroupPhoto != nil
  	fact = fact || m.GroupPhotoDeleted
  	fact = fact || m.GroupCreated || m.SuperGroupCreated
  	fact = fact || (m.MigrateTo != m.MigrateFrom)
  
  	return fact
  }
docs: // IsService returns true, if message is a service message,
  // returns false otherwise.
  //
  // Service messages are automatically sent messages, which
  // typically occur on some global action. For instance, when
  // anyone leaves the chat or chat title changes.