Nevermind, it has it but it's under Computation in polars.Series.diff and I was looking under Aggregation. This is great. For instance you've got a time series

Nevermind, it has it but it's under Computation in polars.Series.diff and I was looking under Aggregation. This is great. For instance you've got a time series with an odometer value and you want the a delta from the previous sample to compute the every trip.