A command line interface built following a tutorial from Real Python.
$ python3 tree.py -v show program's version and exit
$ python3 tree.py -h show a help message and exit
$ python3 tree.py generate a tree directory starting at the working directory (default)
$ python3 tree.py [ROOT_DIR] generate a tree directory of the given directory
eg. $ python3 tree.py ../test :
