input: Write a function to shuffle a list of numbers. If the list is empty, return an empty list.
  
  assert shuffle_list([1, 2, 3, 4, 5])[0] in [1, 2, 3, 4, 5]
  assert shuffle_list([])==[]
  
output: import random
  
  def shuffle_list(lst):
      if not lst:
          return []
      shuffled = lst[:]
      random.shuffle(shuffled)
      return shuffled