code: def extend(self, delta):
  		
  
  		if delta.total_seconds() < 0:
  			raise ValueError("delta must be a positive timedelta.")
  
  		if self.trial_end is not None and self.trial_end > timezone.now():
  			period_end = self.trial_end
  		else:
  			period_end = self.current_period_end
  
  		period_end += delta
  
  		return self.update(prorate=False, trial_end=period_end)
docs: Extends this subscription by the provided delta.
  
  		:param delta: The timedelta by which to extend this subscription.
  		:type delta: timedelta