Checks if the device is in configuration mode or not.

        Arista, unfortunately, does this:
        loc1-core01(s1)#

        Can also be (s2)

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

        Arista, unfortunately, does this:
        loc1-core01(s1)#

        Can also be (s2)
        """
        log.debug("pattern: {0}".format(pattern))
        self.write_channel(self.RETURN)
        output = self.read_until_pattern(pattern=pattern)
        log.debug("check_config_mode: {0}".format(repr(output)))
        output = output.replace("(s1)", "")
        output = output.replace("(s2)", "")
        log.debug("check_config_mode: {0}".format(repr(output)))
        return check_string in output