input: Write a function to return the top 3 numbers from a given array of integers. If the array is empty, return an empty list. Use the sorted function to sort the numbers in descending order and then return the first three elements.
  
  assert top_three([7, 13, 5, 8, 50, 11, 64, 48])==[64, 50, 48]
  assert top_three([1, 2, 3, 4, 5])==[5, 4, 3]
  assert top_three([10, 9, 8, 7, 6])==[10, 9, 8]
  assert top_three([])==[]
output: def top_three(arr):
      return sorted(arr, reverse=True)[:3] if arr else []