For example USI:CVOLM (Call in Miami).
This script subtracts the current cumulative value from the prior cumulative value, so the change/delta in the cumulative value can be determined bar-by-bar.
In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in a publication is governed by House Rules. You can favorite it to use it on a chart.