packageoptionaltypeInt64struct{isSetboolvalueint64}funcNewInt64(valueint64)Int64{returnInt64{true,value,}}// EmptyInt64 returns a new Int64 that does not have a value set.funcEmptyInt64()Int64{returnInt64{false,0,}}func(iInt64)IsSet()bool{returni.isSet}func(iInt64)Value()int64{returni.value}func(iInt64)Default(defaultValueint64)int64{ifi.isSet{returni.value}returndefaultValue}