code: def _validate_region(self):
          
          if not self.region:
              raise GCECloudException(
                  'Zone is required for GCE cloud framework: '
                  'Example: us-west1-a'
              )
  
          try:
              zone = self.compute_driver.ex_get_zone(self.region)
          except Exception:
              zone = None
  
          if not zone:
              raise GCECloudException(
                  '{region} is not a valid GCE zone. '
                  'Example: us-west1-a'.format(
                      region=self.region
                  )
              )
docs: Validate region was passed in and is a valid GCE zone.