input: Write a function to find the largest three numbers in a list. If the list has fewer than three numbers, return the list sorted in descending order. The function should return the largest three numbers as a list.
  
  assert largest_three_numbers([1, 6, 3, 8, 7, 4])==[6, 7, 8]
  assert largest_three_numbers([4, 5, 2])==[2, 4, 5]
  assert largest_three_numbers([1, 2])==[1, 2]
  assert largest_three_numbers([])==[]
  assert largest_three_numbers([9, 8, 10, 11, 7, 6])==[9, 10, 11]
output: def largest_three_numbers(nums):
      if len(nums) < 3:
          return sorted(nums, reverse=True)
      return sorted(nums, reverse=True)[:3]