Question d’entretien chez Copart

Gave a nested array. Make all elements in the nested array into one single array. Like A = [[1, 2, 3 ], [4, 5, 6], 7, 8, [9, 10,[11,1 2]]] , make it [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ]