//ValidchecksConfigdatafunc(c*Config)Valid()Error{//Checkmapping.hostsfor_,raw:=rangec.Mapping.Hosts{ifvalidIP:=utils.ValidIP4(raw.IPAddress);!validIP{err:=new(InvalidIPError)returnerr}}returnnil}//ErrorrepresentserrorsinconfigtypeErrorinterface{Error()string}//InvalidIPErrorraiseswheninvalidipp