old_contents: from __future__ import absolute_import
  
  from .block import Division
  from .element import (Element, html_attribute, boolean_html_attribute,
                        int_html_attribute)
  from .generator import (Generator, NullGenerator, ChildGenerator,
                          HTMLChildGenerator, JoinGenerator, HTMLJoinGenerator)
  from .inline import Span
  
new_contents: from __future__ import absolute_import
  
  from .block import Division
  from .element import (Element, ShortElement,
                        html_attribute, boolean_html_attribute,
                        int_html_attribute)
  from .generator import (Generator, NullGenerator, ChildGenerator,
                          HTMLChildGenerator, JoinGenerator, HTMLJoinGenerator)
  from .inline import Span
  
subject: add missing import for ShortElement