code: func (c *Callbacks) OnCSVCMsg_ServerSteamID(fn func(*dota.CSVCMsg_ServerSteamID) error) {
  	c.onCSVCMsg_ServerSteamID = append(c.onCSVCMsg_ServerSteamID, fn)
  }
docs: // OnCSVCMsg_ServerSteamID registers a callback for SVC_Messages_svc_ServerSteamID