Xstack: An X-ray Spectral Shifting and Stacking Code.

Xstack is a comprehensive standalone pipeline code for X-ray spectral (rest-frame) shifting and stacking. In the era of eROSITA All Sky X-ray Survey (eRASS), the code should be very useful, if you have a special sample (point or extended sources) selected in other bands (infra-red color, optical line/line ratios, variability, etc), and you would like to see how their averaged X-ray spectral shape looks like. You simply download your targets' spectra from eROSITA archive, and Xstack them.