input: Write a function to return the top 3 numbers from a given list of integers in descending order. If the list has fewer than 3 elements, return all available elements.
  
  def top_three(numbers):
      sorted_numbers = sorted(numbers, reverse=True)
      return sorted_numbers[:3]
  
  assert top_three([7, 13, 5, 8, 50, 11, 64, 48])==[64, 50, 48]
  assert top_three([1, 2])==[2, 1]
  assert top_three([1, 2, 3, 4, 5])==[5, 4, 3]
  assert top_three([4, 7, 2, 9, 1, 5])==[9, 7, 5]
  assert top_three([])==[]
output: def top_three(numbers):
      sorted_numbers = sorted(numbers, reverse=True)
      return sorted_numbers[:3]