input: 
  def expand_list(list):
      """The function is attempting to modify the list while iterating over it. This can lead to unexpected behavior and should be avoided. To fix the code, the list should be copied before the iteration takes place.
      
      >>> expand_list([1, 2, 3])
      [1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3]
      """
      list_copy = list[:]   # make a copy of the list
      for item in list_copy:
          list *= 2
      return list
  
output:     list_copy = list[:]   # make a copy of the list
      for item in list_copy:
          list *= 2
      return list