A 
binomial_distribution random number distribution
produces integer values 
i≥0
distributed according to
the discrete probability function
P(i|t,p)=(ti)⋅pi⋅(1−p)t−i .
template<class IntType = int>
  class binomial_distribution {
  public:
        using result_type = IntType;
    using param_type  = unspecified;
        binomial_distribution() : binomial_distribution(1) {}
    explicit binomial_distribution(IntType t, double p = 0.5);
    explicit binomial_distribution(const param_type& parm);
    void reset();
        template<class URBG>
      result_type operator()(URBG& g);
    template<class URBG>
      result_type operator()(URBG& g, const param_type& parm);
        IntType t() const;
    double p() const;
    param_type param() const;
    void param(const param_type& parm);
    result_type min() const;
    result_type max() const;
  };