:param path: str or Path instance
        :return:
        :rtype: dict[str,ValueTree]
        :raises ValueError: A component of path is a field name.
        :raises KeyError: A component of path doesn't exist.

def get_container_containers(self, path):
        """
        :param path: str or Path instance
        :return:
        :rtype: dict[str,ValueTree]
        :raises ValueError: A component of path is a field name.
        :raises KeyError: A component of path doesn't exist.
        """
        container = self.get_container(path)
        containers = {}
        for name,value in container._values.items():
            if isinstance(value, ValueTree):
                containers[name] = value
        return containers