Function builtin_pbinom 

fn builtin_pbinom(
    args: &[RValue],
    named: &[(String, RValue)],
) -> Result<RValue, RError>

Binomial cumulative distribution function.

pbinom(q, size, prob) = sum_{k=0}^{floor(q)} dbinom(k, size, prob) Uses regularized beta: pbinom(k, n, p) = 1 - I_p(k+1, n-k)

@param q quantile vector @param size number of trials @param prob probability of success on each trial @return numeric vector of probabilities