def check_config_mode(self, check_string="", pattern=""):
        """Checks if the device is in configuration mode or not.

        :param check_string: Identification of configuration mode from the device
        :type check_string: str

        :param pattern: Pattern to terminate reading of channel
        :type pattern: str
        """
        self.write_channel(self.RETURN)
        # You can encounter an issue here (on router name changes) prefer delay-based solution
        if not pattern:
            output = self._read_channel_timing()
        else:
            output = self.read_until_pattern(pattern=pattern)
        return check_string in output