docs: def get_domains(self):
          """Retrieves available domains.
  
          Returns:
              :py:obj:`list` of :py:class:`~.rest_primitives.Domain`: List of available domains
          """
          # Domains are fixed and actually only one per REST api.
          if self._domains is None:
              self._domains = self._get_elements('domains', Domain)
          return self._domains