import '@feizheng/next-flatten';

const res = nx.flatten([[1, 2, 3], [4, 5]]); 
// [1, 2, 3, 4, 5]

function flattenArrayOfArrays(a, r) {
  if (!r) { r = [] }
  for (var i = 0; i < a.length; i++) {
    if (a[i].constructor == Array) {
      r.concat(flattenArrayOfArrays(a[i], r));
    } else {
      r.push(a[i]);
    }
  }
  return r;
}