old_contents: #!/usr/bin/env python
  from __future__ import print_function
  from __future__ import unicode_literals
  
new_contents: #!/usr/bin/env python
  from __future__ import print_function
  from __future__ import unicode_literals
  
  
  class Binheap(object):
      ''' Create an empty heap. '''
      def __init__(self):
          self.list = []
  
subject: initialize binheap class with ampty list.