code: func (c *Callbacks) OnCDOTAUserMsg_HalloweenDrops(fn func(*dota.CDOTAUserMsg_HalloweenDrops) error) {
  	c.onCDOTAUserMsg_HalloweenDrops = append(c.onCDOTAUserMsg_HalloweenDrops, fn)
  }
docs: // OnCDOTAUserMsg_HalloweenDrops registers a callback for EDotaUserMessages_DOTA_UM_HalloweenDrops