new_contents: from __future__ import print_function
  import time
  
  
  start_time = None
  
  
  def tic():
      global start_time
      start_time = time.time()
  
  
  def toc(name=None):
      duration = time.time() - start_time
      if name:
          print(name, duration)
      else:
          print(duration)
      return duration
  
subject: Add time_util