aws ec2 describe-regions |
jq -r ".Regions[] | .RegionName" |
ForEach-Object {
    $vpcCidrs = @()
} {
    aws ec2 describe-vpcs --region=$_ |
    jq -r " .Vpcs[] | .CidrBlock" |
    ForEach { if ($_ -ne "172.31.0.0/16") { $vpcCidrs += $_ } }
} {
    $vpcCidrs
}