function skewness( a, b ) {
	if (
		isnan( a ) ||
		isnan( b ) ||
		!isInteger( a ) ||
		!isInteger( b ) ||
		a > b
	) {
		return NaN;
	}
	return 0.0;
}
Returns the skewness of a discrete uniform distribution.

@param {integer} a - minimum support
@param {integer} b - maximum support
@returns {number} skewness

@example
var v = skewness( 0, 1 );
// returns 0.0

@example
var v = skewness( -4, 4 );
// returns 0.0

@example
var v = skewness( 0, 10 );
// returns 0.0

@example
var v = skewness( 1, -0.1 );
// returns NaN

@example
var v = skewness( -0.1, 1 );
// returns NaN

@example
var v = skewness( 2, NaN );
// returns NaN

@example
var v = skewness( NaN, 2 );
// returns NaN