function incrmax() {
	var max;
	return accumulator;

	/**
	* If provided a value, the accumulator function returns an updated maximum value. If not provided a value, the accumulator function returns the current max.
	*
	* @private
	* @param {number} [x] - new value
	* @returns {(number|null)} max value or null
	*/
	function accumulator( x ) {
		if ( arguments.length === 0 ) {
			return ( max === void 0 ) ? null : max;
		}
		if (
			max === void 0 ||
			x > max ||
			isnan( x ) ||
			( x === max && isPositiveZero( x ) )
		) {
			max = x;
		}
		return max;
	}
}
Returns an accumulator function which incrementally computes a maximum value.

@returns {Function} accumulator function

@example
var accumulator = incrmax();

var max = accumulator();
// returns null

max = accumulator( 3.14 );
// returns 3.14

max = accumulator( -5.0 );
// returns 3.14

max = accumulator( 10.1 );
// returns 10.1

max = accumulator();
// returns 10.1