function binomial2( n, p ) {
		if (
			isnan( n ) ||
			isnan( p ) ||
			!isPositiveInteger( n ) ||
			!isProbability( p )
		) {
			return NaN;
		}
		return binomial0( rand, n, p );
	}
Returns a random number drawn from a binomial distribution.

@private
@param {PositiveInteger} n - number of trials
@param {Probability} p - success probability
@returns {NonNegativeInteger} pseudorandom number

@example
var r = binomial2( 20, 0.8 );
// returns <number>