code: def format_time(start, end):
      
      try:
          cpu_usr = end[0] - start[0]
          cpu_sys = end[1] - start[1]
  
      except TypeError:
          # `clock()[1] == None` so subtraction results in a TypeError
          return 'Time elapsed: {}'.format(human_time(cpu_usr))
  
      else:
          times = (human_time(x) for x in (cpu_usr, cpu_sys, cpu_usr + cpu_sys))
          return 'Time elapsed: user: {}, sys: {}, total: {}'.format(*times)
docs: Returns string with relevant time information formatted properly