def METHOD_NAME(express_route_gateway_name: Optional[pulumi.Input[str]] = None,
                                     resource_group_name: Optional[pulumi.Input[str]] = None,
                                     opts: Optional[pulumi.InvokeOptions] = None) -> pulumi.Output[GetExpressRouteGatewayResult]:
    """
    Fetches the details of a ExpressRoute gateway in a resource group.
    :param str express_route_gateway_name: The name of the ExpressRoute gateway.
    :param str resource_group_name: The name of the resource group.
    """
    ...