import { createDuration } from ‘./create’;

function addSubtract (duration, input, value, direction) {

var other = createDuration(input, value);

duration._milliseconds += direction * other._milliseconds;
duration._days         += direction * other._days;
duration._months       += direction * other._months;

return duration._bubble();

}

// supports only 2.0-style add(1, ‘s’) or add(duration) export function add (input, value) {

return addSubtract(this, input, value, 1);

}

// supports only 2.0-style subtract(1, ‘s’) or subtract(duration) export function subtract (input, value) {

return addSubtract(this, input, value, -1);

}