old_contents: from mdx_linkify.mdx_linkify import makeExtension
  
new_contents: import sys
  
  
  is_python3 = sys.version_info >= (3, 0)
  
  if is_python3:
      from mdx_linkify.mdx_linkify import makeExtension
  else:
      from mdx_linkify import makeExtension
  
  
  assert makeExtension  # Silences pep8.
  
subject: Fix import for python2 and pypy