pmf
Returns the probability mass at k for this binomial distribution.
Computes the exact probability of observing exactly k successes in trials independent trials. Returns zero for values outside the support (k < 0 or k > trials). Handles the degenerate cases where the success probability is 0 or 1 directly.
Return
the probability of exactly k successes, in the range [0, 1].
Parameters
k
the number of successes at which to evaluate the probability.