import { flatten } from "array-flatten";
 
flatten([1, [2, [3, [4, [5], 6], 7], 8], 9]);
//=> [1, 2, 3, 4, 5, 6, 7, 8, 9]
//=> [1, 2, 3, 4, 5, 6, 7, 8, 9]
 
(function() {
  flatten(arguments); //=> [1, 2, 3]
//=> [1, 2, 3]
})(1, [2, 3]);

const array = [1, [2, 3]];

const flattenedArray = Hoek.flatten(array); // results in [1, 2, 3]

array = [1, [2, 3]];
target = [4, [5]];

flattenedArray = Hoek.flatten(array, target); // results in [4, [5], 1, 2, 3]

var array = [1, [2, [3, [4]], 5]];
 
_.flattenDepth(array, 1);
// => [1, 2, [3, [4]], 5]
 
_.flattenDepth(array, 2);
// => [1, 2, 3, [4], 5]

_.flatten([1, [2], [3, [[4]]]]);
// => [1, 2, 3, 4];

_.flatten([1, [2], [3, [[4]]]], true);
// => [1, 2, 3, [[4]]];

_.flatten([1, [2], [3, [[4]]]], 2);
// => [1, 2, 3, [4]];

import {flatten} from 'rambda'

describe('flatten', () => {
  it('happy', () => {
    const result = flatten<number>([1, 2, [3, [4]]])
    result // $ExpectType number[]
  })
})