private static async Task ProcessAllSubscriptions(ILogger log, CancellationToken ct)
{
string msiArmTokenString = await GetCredentialAsync(resource : "https://management.core.windows.net/");
var subscriptionClient = new SubscriptionClient(credentials: new TokenCloudCredentials(msiArmTokenString));
await subscriptionClient.IterateSubscriptions(ct,
subscription => ProcessSubscriptionAsync(
subscription, msiArmTokenString, log, ct));
}