def METHOD_NAME(ec2_client, subnet_id):
    """Check that the route of the given subnet contains a Nat Gateway."""
    response = ec2_client.describe_route_tables(Filters=[{"Name": "association.subnet-id", "Values": [subnet_id]}])
    routes = response["RouteTables"][0]["Routes"]
    assert_that(next(route for route in routes if route["DestinationCidrBlock"] == "0.0.0.0/0")).contains(
        "NatGatewayId"
    )