Exit from configuration mode.

        :param exit_config: Command to exit configuration mode
        :type exit_config: str

        :param pattern: Pattern to terminate reading of channel
        :type pattern: str

def exit_config_mode(self, exit_config="", pattern=""):
        """Exit from configuration mode.

        :param exit_config: Command to exit configuration mode
        :type exit_config: str

        :param pattern: Pattern to terminate reading of channel
        :type pattern: str
        """
        output = ""
        if self.check_config_mode():
            self.write_channel(self.normalize_cmd(exit_config))
            output = self.read_until_pattern(pattern=pattern)
            if self.check_config_mode():
                raise ValueError("Failed to exit configuration mode")
        log.debug("exit_config_mode: {}".format(output))
        return output