docs: def flush(self, safe=None):
  		''' Perform all database operations currently in the queue'''
  		result = None
  		for index, op in enumerate(self.queue):
  			try:
  				result = op.execute()
  			except:
  				self.clear_queue()
  				self.clear_cache()
  				raise
  		self.clear_queue()
  		return result