ImportError: No module named pymol

I run a python script, but it returns this error. I am working on an environment and I believe that I have to install the pymol module. I am not familiar with these things and I have no idea how to solve this problem. Could anyone guide me? This is the command I use to invoke the environment: source env_prova/bin/activate This is the command for the script: python pymol_align.py --list1=list.txt --list2= template.txt --out= pr.txt This is the error: Traceback (most recent call last): File "pymol_align.py", line 4, in import pymol ImportError: No module named pymol Could someone help me?