Create an handler for at specific level.

def _create_handler(self, handler_class, level):
        """Create an handler for at specific level."""
        if handler_class == logging.StreamHandler:
            handler = handler_class()
            handler.setLevel(level)
        elif handler_class == logging.handlers.SysLogHandler:
            handler = handler_class(address='/dev/log')
            handler.setLevel(level)
        elif handler_class == logging.handlers.TimedRotatingFileHandler:
            handler = handler_class(self.filename, when='midnight')
            handler.setLevel(level)
        elif handler_class == AlkiviEmailHandler:
            handler = handler_class(mailhost='127.0.0.1',
                                    fromaddr="%s@%s" % (USER, HOST),
                                    toaddrs=self.emails,
                                    level=self.min_log_level_to_mail)
            # Needed, we want all logs to go there
            handler.setLevel(0)

        formatter = self.get_formatter(handler)
        handler.setFormatter(formatter)
        self.handlers.append(handler)
        self.logger.addHandler(handler)