Q:

AWS CloudFormation Outputs: Exporting AZ's

Creating a layered stack set in cloudformation. Network Stack and App Stack
.
I have a requirement to export the AZ's from the Network Stack.
I have tried the following:
"Outputs": {
    "AZs": {
        "Description": "AZs",
        "Value": {
            "Fn::GetAtt": [
                "Network