Vivisica, to the best of my knowledge argparse should be installed on BIG-IQ, though yours is not the first report I've heard of it not being found. What version of BIG-IQ are you running? I would try the following and look for anything fishy:
This tells me that argparse is installed in site-packages, which is (of course) present in the python system path. You could try checking that argparse is present in your site-packages folder, and that site-packages is in the python path.