code: def endStep(self,key):
          
          ptime = _ptime()
          if key is not None:
              self.steps[key]['end'] = ptime
              self.steps[key]['elapsed'] = ptime[1] - self.steps[key]['start'][1]
          self.end = ptime
  
          print('==== Processing Step ',key,' finished at ',ptime[0])
          print('')
docs: Record the end time for the step.
  
          If key==None, simply record ptime as end time for class to represent
          the overall runtime since the initialization of the class.