Checks current usage against configured thresholds for all limits
        for this service.

        :returns: a dict of limit name to :py:class:`~.AwsLimit` instance
          for all limits that crossed one or more of their thresholds.
        :rtype: :py:obj:`dict` of :py:class:`~.AwsLimit`

def check_thresholds(self):
        """
        Checks current usage against configured thresholds for all limits
        for this service.

        :returns: a dict of limit name to :py:class:`~.AwsLimit` instance
          for all limits that crossed one or more of their thresholds.
        :rtype: :py:obj:`dict` of :py:class:`~.AwsLimit`
        """
        if not self._have_usage:
            self.find_usage()
        ret = {}
        for name, limit in self.limits.items():
            if limit.check_thresholds() is False:
                ret[name] = limit
        return ret