old_contents: from __future__ import print_function
  from __future__ import division
  
  
  def _gap_insertion_sort(a_list, start, gap):
      for i in range(start + gap, len(a_list), gap):
          current_value = a_list[i]
          position = i
  
          while (position >= gap) and (a_list[position - gap] > current_value):
              a_list[position] = a_list[position - gap]
              position = position - gap
  
          a_list[position] = current_value
  
  
  def shell_sort(a_list):
      """Shell Sort algortihm."""
      sublist_count = len(a_list) // 2
      while sublist_count > 0:
          for start_pos in range(sublist_count):
              _gap_insertion_sort(a_list, start_pos, sublist_count)
          
          print('After increments of size {0}, a_list is \n{1}'
                .format(sublist_count, a_list))
  
          sublist_count = sublist_count // 2
  
  
  def main():
      a_list = [54, 26, 93, 17, 77, 31, 44, 55, 20]
      print('a_list: \n{}'.format(a_list))
      print('By Shell Sort: ')
      shell_sort(a_list)
  
  
  if __name__ == '__main__':
      main()
  
new_contents: from __future__ import absolute_import
  from __future__ import print_function
  from __future__ import division
  
  
  def _gap_insertion_sort(a_list, start, gap):
      for i in range(start + gap, len(a_list), gap):
          current_value = a_list[i]
          position = i
  
          while (position >= gap) and (a_list[position - gap] > current_value):
              a_list[position] = a_list[position - gap]
              position = position - gap
  
          a_list[position] = current_value
  
  
  def shell_sort(a_list):
      """Shell Sort algortihm."""
      sublist_count = len(a_list) // 2
      while sublist_count > 0:
          for start_pos in range(sublist_count):
              _gap_insertion_sort(a_list, start_pos, sublist_count)
          
          print('After increments of size {0}, a_list is \n{1}'
                .format(sublist_count, a_list))
  
          sublist_count = sublist_count // 2
  
  
  def main():
      a_list = [54, 26, 93, 17, 77, 31, 44, 55, 20]
      print('a_list: \n{}'.format(a_list))
      print('By Shell Sort: ')
      shell_sort(a_list)
  
  
  if __name__ == '__main__':
      main()
  
subject: Add default import