function incrnanskewness() {
	var skewness = incrskewness();
	return accumulator;

	/**
	* If provided a value, the accumulator function returns an updated corrected sample skewness. If not provided a value, the accumulator function returns the current corrected sample skewness.
	*
	* @private
	* @param {number} [x] - new value
	* @returns {(number|null)} corrected sample skewness or null
	*/
	function accumulator( x ) {
		if ( arguments.length === 0 || isnan( x ) ) {
			return skewness();
		}
		return skewness( x );
	}
}
Returns an accumulator function which incrementally computes a corrected sample skewness, ignoring `NaN` values.

@returns {Function} accumulator function

@example
var accumulator = incrnanskewness();

var skewness = accumulator();
// returns null

skewness = accumulator( 2.0 );
// returns null

skewness = accumulator( -5.0 );
// returns null

skewness = accumulator( -10.0 );
// returns ~0.492

skewness = accumulator( NaN );
// returns ~0.492

skewness = accumulator();
// returns ~0.492