def save(self, filename=None):
        filename = Path(filename) if filename is not None else self.filename
        with filename.open("w") as f:
            f.write(self.yaml)
def get_primary_domain(self):
        """
        Returns the primary domain of the tenant
        """
        try:
            domain = self.domains.get(is_primary=True)
            return domain
        except get_tenant_domain_model().DoesNotExist:
            return None