docs: def main():
      '''main routine'''
  
      # process arguments
      if len(sys.argv) < 3:
          usage()
  
      rgname = sys.argv[1]
      vmss_name = sys.argv[2]
  
      # Load Azure app defaults
      try:
          with open('azurermconfig.json') as config_file:
              config_data = json.load(config_file)
      except FileNotFoundError:
          sys.exit('Error: Expecting azurermonfig.json in current folder')
  
      tenant_id = config_data['tenantId']
      app_id = config_data['appId']
      app_secret = config_data['appSecret']
      subscription_id = config_data['subscriptionId']
  
      access_token = azurerm.get_access_token(tenant_id, app_id, app_secret)
  
      instanceviewlist = azurerm.list_vmss_vm_instance_view(access_token, subscription_id, rgname,
                                                            vmss_name)
      for vmi in instanceviewlist['value']:
          instance_id = vmi['instanceId']
          upgrade_domain = vmi['properties']['instanceView']['platformUpdateDomain']
          fault_domain = vmi['properties']['instanceView']['platformFaultDomain']
          print('Instance ID: ' + instance_id + ', UD: ' + str(upgrade_domain) + ', FD: '
                + str(fault_domain))