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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def patterson_fst(aca, acb):
 """Estimator of differentiation between populations A and B based on the F2 parameter. Parameters aca : array_like, int, shape (n_variants, 2) Allele counts for population A. acb : array_like, int, shape (n_variants, 2) Allele counts for population B. Returns ------- num : ndarray, shape (n_variants,), float Numerator. den : ndarray, shape (n_variants,), float Denominator. Notes ----- See Patterson (2012), Appendix A. TODO check if this is numerically equivalent to Hudson's estimator. """


    from allel.stats.admixture import patterson_f2, h_hat
    num = patterson_f2(aca, acb)
    den = num + h_hat(aca) + h_hat(acb)

    return num, den