copy POTCAR from your vasp-package to start this example (example doesnot contain POTCAR)
make sure INCAR POTCAR POSCAR KPOINTS exist 
Edit your test.py and strain.dat if require
uncomment eg.cubic_pre() 
run python3 test.py
This will generate C11_C12_I C11_C12_II C44 folder
Each folder contain different strain folder
copy INCAR KPOINTS POTCAR and run.pbs into each strain folder inside each all 3 folder
you can use copy.sh for copying and running vasp also 
Once each folder calculation complete
edit test.py and uncomment post-processing constants.cubic_post() (don't forget to comment pre-processing one)
you are done
