function quantile( r, p ) {
	return addon( r, p );
}
Evaluates the quantile function for a Bernoulli distribution with success probability `p` at a probability `r`.

@private
@param {Probability} r - input value
@param {Probability} p - success probability
@returns {NonNegativeNumber} evaluated quantile function

@example
var y = quantile( 0.8, 0.4 );
// returns 1.0

@example
var y = quantile( 0.5, 0.4 );
// returns 0.0

@example
var y = quantile( 0.8, 0.1 );
// returns 0.0

@example
var y = quantile( -0.2, 0.1 );
// returns NaN

@example
var y = quantile( NaN, 0.8 );
// returns NaN

@example
var y = quantile( 0.4, NaN );
// returns NaN

@example
var y = quantile( 0.5, -1.0 );
// returns NaN

@example
var y = quantile( 0.5, 1.5 );
// returns NaN