input: Write a python function to generate an array of random numbers and a random index, then return the number at that index.
  assert random_index_number([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 2) == 3
  assert random_index_number([10, 20, 30, 40, 50], 4) == 50
  assert random_index_number([5, 7, 9, 8, 6, 4, 3], 1) == 7
output: import random
  
  def random_index_number(arr, index):
      random_index = random.randint(0, len(arr) - 1)
      return arr[random_index] if index >= len(arr) else arr[index]