def target_exists(self, target_id=0):
        """
        Returns True or False indicating whether or not the specified
        target is present and valid.

        `target_id` is a target ID (or None for the first target)
        """
        try:
            target = self._target(target_id=target_id)
        except Exception as e:
            log.error("Exception checking if target exists: {} {}".format(type(e), e))
            return False
        return target is not None