code: def timestamp(val):  
      
      
      
      
      if val is 'on':
          todaystring = datetime.datetime.now().strftime('%Y-%m-%d %H%M%S')
          extra_layouts['time_stamp'] = todaystring
      else:
          if 'time_stamp' in extra_layouts:
              del extra_layouts['time_stamp']
      
      return
docs: This function will turn on a time stamp that shows up at the bottom of every generated plot.
      
      Parameters
          val  str
              A string that can either be 'on' or 'off'.  
              
      Returns
          None
      
      Examples
           # Turn on the timestamp
           import pytplot
           pytplot.timestamp('on')