Get_activity from depeltion_results.h5 (OpenMC 0.13.2)

Dear Friends,
I am encountering an AttributeError: 'Results' object has no attribute 'get_activity' while trying to retrieve activity from depletion_results.h5. I am using OpenMC version 0.13.2. Could someone please confirm whether this option is available in this version (0.13.2)?

With thanks & best regards,
L Thilagam