function accumulator( x ) {
		if ( arguments.length === 0 ) {
			return max();
		}
		return max( abs( x ) );
	}
If provided a value, the accumulator function returns an updated maximum absolute value. If not provided a value, the accumulator function returns the current maximum absolute value.

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