scipy.stats._discrete_distns.binom
https://docs.scipy.org/doc/scipy/reference/generated/scipy.stats.binom.html
scipy.stats.distributions.binom
cdf(k, n, p, loc=0)
Cumulative distribution function.
https://github.com/scipy/scipy/blob/v1.9.3/scipy/stats/_discrete_distns.py#L112
分布の実装は
binom_gen
https://github.com/scipy/scipy/blob/v1.9.3/scipy/stats/_discrete_distns.py#L30-L109