old_contents: from __future__ import absolute_import, division, print_function
  
  from .core import (Bag, Item, from_sequence, from_filenames, from_hdfs,
          from_url, to_textfiles, concat)
  from ..context import set_options
  
new_contents: from __future__ import absolute_import, division, print_function
  
  from .core import (Bag, Item, from_sequence, from_filenames, from_hdfs,
                     from_url, to_textfiles, concat, from_s3)
  from ..context import set_options
  
subject: Add from_s3 to namespace