How to compare current value in a real time stream data with previous value in tickscript?

I am working on kapacitor alerts to generate alerts on data in influxDB. I am receiving a new value from the stream when a request has been made. I want to compare the current value in my stream I received with the previous value I received just before it to see if current value is greater than previous value or not. If it is greater than previous value, then I want to generate an alert on chronograf using kapacitor and tickscript.

How do I achieve this in tickscript?

The issue mentions Kapacitor, InfluxDB, Chronograf, and TICKscript but names no repository files or tests. Start by checking the existing TICKscript stream-operator documentation and examples for comparing successive values; done would be a clear documented example answering this use case.

Written by the indexing model from the issue text.