input: Write a function to find the largest three numbers in a given list. If the list has fewer than three numbers, return all the numbers sorted in descending order. If the list is empty, return an empty list.
  assert find_largest_three_numbers([1, 6, 3, 8, 7, 4])==[6, 7, 8]
  assert find_largest_three_numbers([10, 20])==[10, 20]
  assert find_largest_three_numbers([])==[]
  assert find_largest_three_numbers([5, 5, 5, 5])==[5, 5, 5]
  assert find_largest_three_numbers([4, 3, 2, 1])==[2, 3, 4]
output: def find_largest_three_numbers(nums):
      if len(nums) == 0:
          return []
      elif len(nums) < 3:
          return sorted(nums, reverse=True)
      else:
          return sorted(nums, reverse=True)[:3]