docs: def validate(self):
  		'''Validate required headers and validate notification headers'''
  		for header in self._requiredHeaders:
  			if not self.headers.get(header, False):
  				raise errors.ParseError('Missing Registration Header: ' + header)
  		for notice in self.notifications:
  			for header in self._requiredNotificationHeaders:
  				if not notice.get(header, False):
  					raise errors.ParseError('Missing Notification Header: ' + header)