old_contents: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  
  def prim():
  	pass
  
  
  def main():
  	pass
  
  
  if __name__ == '__main__':
  	main()
  
new_contents: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  
  def prim():
  	"""Prim's Minimum Spanning Tree."""
  	pass
  
  
  def main():
  	pass
  
  
  if __name__ == '__main__':
  	main()
  
subject: Add doc string