def get_limits(self):
        """
        Return all known limits for this service, as a dict of their names
        to :py:class:`~.AwsLimit` objects.

        :returns: dict of limit names to :py:class:`~.AwsLimit` objects
        :rtype: dict
        """
        if self.limits != {}:
            return self.limits
        limits = {}
        limits['Groups'] = AwsLimit(
            'Groups',
            self,
            300,
            self.warning_threshold,
            self.critical_threshold,
            limit_type='AWS::IAM::Group',
        )
        limits['Users'] = AwsLimit(
            'Users',
            self,
            5000,
            self.warning_threshold,
            self.critical_threshold,
            limit_type='AWS::IAM::User',
        )
        limits['Roles'] = AwsLimit(
            'Roles',
            self,
            1000,
            self.warning_threshold,
            self.critical_threshold,
            limit_type='AWS::IAM::Role',
        )
        limits['Instance profiles'] = AwsLimit(
            'Instance profiles',
            self,
            1000,
            self.warning_threshold,
            self.critical_threshold,
            limit_type='AWS::IAM::InstanceProfile',
        )
        limits['Server certificates'] = AwsLimit(
            'Server certificates',
            self,
            20,
            self.warning_threshold,
            self.critical_threshold,
            limit_type='AWS::IAM::ServerCertificate',
        )
        limits['Policies'] = AwsLimit(
            'Policies',
            self,
            1500,
            self.warning_threshold,
            self.critical_threshold,
            limit_type='AWS::IAM::Policy',
        )
        limits['Policy Versions In Use'] = AwsLimit(
            'Policy Versions In Use',
            self,
            10000,
            self.warning_threshold,
            self.critical_threshold,
            limit_type='AWS::IAM::ServerCertificate',
        )
        self.limits = limits
        return limits