How to use the node-opcua-client.ClientMonitoredItem.create function in node-opcua-client

});
        subscription.on("keepalive", () => {
            console.log(" Keep Alive");
        });

        const parameters1: MonitoringParametersOptions = {
            discardOldest: true,
            queueSize: 100,
            samplingInterval: 250
        };
        const itemToMonitor1: ReadValueIdLike = {
            attributeId: AttributeIds.Value,
            nodeId: "ns=1;s=PumpSpeed"
        };

        const item1 = ClientMonitoredItem.create(subscription, itemToMonitor1, parameters1, TimestampsToReturn.Both);
        item1
            .on("changed", (dataValue: DataValue) => {
                console.log(" Value1 has changed : ", dataValue.toString());
            })
            .on("terminated", () => {
                console.log("item1 has been terminated");
            });

        const itemToMonitor2: ReadValueIdLike = {
            attributeId: AttributeIds.Value,
            nodeId: "ns=1;s=FanSpeed"
        };
        const item2 = ClientMonitoredItem.create(subscription, itemToMonitor2, parameters1, TimestampsToReturn.Both);
        item2
            .on("changed", (dataValue: DataValue) => {
                console.log(" Value2 has changed : ", dataValue.toString());

};

        const item1 = ClientMonitoredItem.create(subscription, itemToMonitor1, parameters1, TimestampsToReturn.Both);
        item1
            .on("changed", (dataValue: DataValue) => {
                console.log(" Value1 has changed : ", dataValue.toString());
            })
            .on("terminated", () => {
                console.log("item1 has been terminated");
            });

        const itemToMonitor2: ReadValueIdLike = {
            attributeId: AttributeIds.Value,
            nodeId: "ns=1;s=FanSpeed"
        };
        const item2 = ClientMonitoredItem.create(subscription, itemToMonitor2, parameters1, TimestampsToReturn.Both);
        item2
            .on("changed", (dataValue: DataValue) => {
                console.log(" Value2 has changed : ", dataValue.toString());
            })
            .on("terminated", () => {
                console.log("item2 has been terminated");
            });

        await timeout(10000);

        await subscription.terminate();

        await client.disconnect();

        console.log(" Done!");