function skewness( p ) {
	if (
		isnan( p ) ||
		p < 0.0 ||
		p > 1.0
	) {
		return NaN;
	}
	if ( p === 0.0 ) {
		return PINF;
	}
	if ( p === 1.0 ) {
		return NINF;
	}
	return ( 1.0 - ( 2.0*p ) ) / sqrt( p * ( 1.0-p ) );
}
Returns the skewness of a Bernoulli distribution.

@param {Probability} p - success probability
@returns {PositiveNumber} skewness

@example
var v = skewness( 0.1 );
// returns ~2.667

@example
var v = skewness( 0.5 );
// returns 0.0

@example
var v = skewness( 1.1 );
// returns NaN

@example
var v = skewness( NaN );
// returns NaN