subnet1a=aws.ec2.Subnet( "subnet1a", vpc_id=vpc1.id, availability_zone=networks["zone1a"], tags={ "Name": "subnet1a" }, cidr_block=networks["public1"], ipv6_cidr_block=pulumi.Output.concat(vpc1.ipv6_cidr_block, "16a::/64") ) it come with error at ipv6 cidr block