Mark an instance and all of its databases for permanent deletion.

        See
        https://cloud.google.com/spanner/reference/rpc/google.spanner.admin.instance.v1#google.spanner.admin.instance.v1.InstanceAdmin.DeleteInstance

        Immediately upon completion of the request:

        * Billing will cease for all of the instance's reserved resources.

        Soon afterward:

        * The instance and all databases within the instance will be deleteed.
          All data in the databases will be permanently deleted.

def delete(self):
        """Mark an instance and all of its databases for permanent deletion.

        See
        https://cloud.google.com/spanner/reference/rpc/google.spanner.admin.instance.v1#google.spanner.admin.instance.v1.InstanceAdmin.DeleteInstance

        Immediately upon completion of the request:

        * Billing will cease for all of the instance's reserved resources.

        Soon afterward:

        * The instance and all databases within the instance will be deleteed.
          All data in the databases will be permanently deleted.
        """
        api = self._client.instance_admin_api
        metadata = _metadata_with_prefix(self.name)

        api.delete_instance(self.name, metadata=metadata)