old_contents: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  
  
  class Vertex(object):
  	"""Vertex class.
  
      It uses a dict to keep track of the vertices which it's connected.
  	"""
  
  
  class Graph(object):
      """Graph class.
  
      It contains a dict to map vertex name to vertex objects.
      """
      pass
  
  
  def main():
      pass
  
  
  if __name__ == '__main__':
      main()
  
new_contents: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  
  
  class Vertex(object):
  	"""Vertex class.
  
      It uses a dict to keep track of the vertices which it's connected.
  	"""
  	def __init__(self, key):
  		self.id = key
  		self.connected_to_dict = {}
  
  	def add_neighnor(self, new_nb, weight=0):
  		pass
  
  	def __str__(self):
  		pass
  
  	def get_connections(self):
  		pass
  
  	def get_id(self):
  		pass
  
  	def get_weight(self, new_nb):
  		pass
  
  
  class Graph(object):
      """Graph class.
  
      It contains a dict to map vertex name to vertex objects.
      """
      pass
  
  
  def main():
      pass
  
  
  if __name__ == '__main__':
      main()
  
subject: Implement Vertex class’s __init__ and helper functions