input: Write a function to find the largest three numbers in a given list. If the list has fewer than three elements, return all the elements in descending order. If the list is empty, return an empty list.
  assert find_largest_three([1, 6, 3, 8, 7, 4])==[8, 7, 6]
  assert find_largest_three([5, 2, 9])==[9, 5, 2]
  assert find_largest_three([7])==[7]
  assert find_largest_three([])==[]
output: def find_largest_three(lst):
      if not lst:
          return []
      sorted_lst = sorted(lst, reverse=True)
      return sorted_lst[:3]