drivers/azure/azureutil/azureutil.go
func (a AzureClient) CleanupVirtualNetworkIfExists(resourceGroup, name string) error {
	return a.cleanupResourceIfExists(&vnetCleanup{rg: resourceGroup, name: name})
}
func (a AzureClient) CleanupVirtualNetworkIfExists(resourceGroup, name string) error {
	return a.cleanupResourceIfExists(&vnetCleanup{rg: resourceGroup, name: name})
}
// CleanupVirtualNetworkIfExists removes a subnet if there are no subnets
// attached to it. Note that this method is not safe for multiple concurrent
// writers, in case of races, deployment of a machine could fail or resource
// might not be cleaned up.