def _create_subnet(self, resource_group_name, subnet_id, vnet_name):
        """
        Create a subnet in the provided vnet and resource group.
        """
        subnet_config = {'address_prefix': '10.0.0.0/29'}

        try:
            subnet_setup = self.network.subnets.create_or_update(
                resource_group_name, vnet_name, subnet_id, subnet_config
            )
        except Exception as error:
            raise AzureCloudException(
                'Unable to create subnet: {0}.'.format(error)
            )

        return subnet_setup.result()
Create a subnet in the provided vnet and resource group.