function accumulator( x ) {
		if ( arguments.length === 0 ) {
			return ( min === void 0 ) ? null : min;
		}
		if (
			min === void 0 ||
			x < min ||
			isnan( x ) ||
			( x === min && isNegativeZero( x ) )
		) {
			min = x;
		}
		return min;
	}
If provided a value, the accumulator function returns an updated minimum value. If not provided a value, the accumulator function returns the current min.

@private
@param {number} [x] - new value
@returns {(number|null)} min value or null