def split_alpha_beta(self):
        rules_alpha = []    # a      -> b
        rules_beta = []     # &(...) -> b
        for a, b in self.proved_rules:
            if isinstance(a, And):
                rules_beta.append((a, b))
            else:
                rules_alpha.append((a, b))
        return rules_alpha, rules_beta
split proved rules into alpha and beta chains
dataset/ETHPy150Open sympy/sympy/sympy/core/facts.py/Prover.split_alpha_beta