With the major version of ISIS being ticked up to 4 there is a significant problem in the env.py file code. It checks for a major version equal to 3 (== 3) to do some of its setup when it should probably be checking for a version greater than or equal to 3 (>= 3). This will cause problems going forward when trying use pysis with any version of ISIS 4.

Could the logic in the env.py be updated to accommodate current versions of ISIS 4?