old_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, binlist=[]):
          self.binlist = binlist
  
      def push(self, value):
          self.binlist.append[value]
          return
  
      def pop(self):
          return self.binlist.pop([0])
  
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, binlist=[]):
          self.binlist = binlist
  
      def push(self, value):
          self.binlist.append[value]
          return
  
      def pop(self):
          top = self.binlist[0]
          if self.binlist[2] >= self.binlist[1]:
              self.binlist[0] = self.binlist[2]
          else:
              self.binlist[0] = self.binlist[1]
          return top
  
subject: fix pop method to promote children.