(PECL stats >= 1.0.0)
stats_dens_pmf_binomial — Probability mass function of the binomial distribution
   Returns the probability mass at x, where the random variable
   follows the binomial distribution of which the number of trials is n
   and the success rate is pi.
  
xThe value at which the probability mass is calculated
nThe number of trials of the distribution
piThe success rate of the distribution
   The probability mass at x or false for failure.
  
