code: func (c *Callbacks) OnCDOTAUserMsg_ItemPurchased(fn func(*dota.CDOTAUserMsg_ItemPurchased) error) {
  	c.onCDOTAUserMsg_ItemPurchased = append(c.onCDOTAUserMsg_ItemPurchased, fn)
  }
docs: // OnCDOTAUserMsg_ItemPurchased registers a callback for EDotaUserMessages_DOTA_UM_ItemPurchased