new_contents: __author__ = 'yue'
  
  
  class Node:
  
      def __init__(self):
          self.character = ''
          self.frequency = 0
          self.left = None
          self.right = None
  
      def __init__(self, ch, freq):
          self.character = ch
          self.frequency = freq
          self.left = None
          self.right = None
  
      def is_leaf(self):
          return not self.left and not self.right
subject: add not tested yet: cpr_in_python/node.py