The same way as in the question you linked.
subprocess.call(['./abc.py', '--help'])
or
subprocess.call(['./abc.py', '-f', 'FOLDER'])
You can think the list of flags and options supplied for the call-method just as different way to passing those arguments. If you would call that python-file normally from command-line, you would supply those arguments separated with space, so in a way it is a space separated list. Here the same list is supplied, just in a different format, where each , separates the arguments instead of the space.