docs: def keep_alive(self):
  
  		'''
  		Keep current transaction alive, updates self.expires
  
  		Args:
  			None
  
  		Return:
  			None: sets new self.expires
  		'''
  
  		# keep transaction alive
  		txn_response = self.api.http_request('POST','%sfcr:tx' % self.root, data=None, headers=None)
  
  		# if 204, transaction kept alive
  		if txn_response.status_code == 204:
  			logger.debug("continuing transaction: %s" % self.root)
  			# update status and timer
  			self.active = True
  			self.expires = txn_response.headers['Expires']
  			return  True
  
  		# if 410, transaction does not exist
  		elif txn_response.status_code == 410:
  			logger.debug("transaction does not exist: %s" % self.root)
  			self.active = False
  			return False
  
  		else:
  			raise Exception('HTTP %s, could not continue transaction' % txn_response.status_code)