@classmethod
    def get_root_nodes(cls):  # pragma: no cover
        raise NotImplementedError
Expectation of expression over distribution
dataset/ETHPy150Open tabo/django-treebeard/treebeard/models.py/Node.get_root_nodes--crossover with--dataset/ETHPy150Open sympy/sympy/sympy/stats/drv.py/SingleDiscreteDistribution.expectation