find usage for Internet Gateways

def _find_usage_gateways(self):
        """find usage for Internet Gateways"""
        # Internet gateways
        gws = self.conn.describe_internet_gateways()
        self.limits['Internet gateways']._add_current_usage(
            len(gws['InternetGateways']),
            aws_type='AWS::EC2::InternetGateway',
        )