input: Write a python function to multiply elements of inner arrays by their respective outer array indices.
  assert arrayMultiplied([[1, 2, 3], [4, 5, 6]]) == [[0, 2, 6], [0, 5, 12]]
  assert arrayMultiplied([[2, 3], [1, 2, 3], [4, 5, 6]]) == [[0, 0], [0, 2, 3], [0, 5, 12]]
  assert arrayMultiplied([[1], [2], [3]]) == [[0], [0], [6]]
output: def arrayMultiplied(arr):
      result = []
      for i, sublist in enumerate(arr):
          result.append([i * elem for elem in sublist])
      return result