input: Write a python function to calculate the probability of getting at least one "6" when rolling a specified number of six-sided dice.
  assert two_dice_same(1) == 1/6
  assert two_dice_same(2) == 11/36
  assert two_dice_same(3) == 91/216
output: def two_dice_same(n):
      return 1 - ((5/6) ** n)