new_contents: #!/usr/bin/env python
  # encoding: utf-8
  
  from __future__ import division, print_function
  from time import time
  
  
  class Timer(object):
  
      """ Simple timing object.
  
      Usage:
          with Timer('Function took'):
              do_something()
      """
  
      def __init__(self, msg='Timer'):
          """
          :msg: Additional message to show after finishing timing.
  
          """
          self._msg = msg
  
      def __enter__(self):
          self._start = time()
  
      def __exit__(self, *args):
          print('{}: {}s'.format(self._msg, time() - self._start))
  
subject: Add timer class