python script works with hard coded string, but not string wrapped command line argument code example

Example: argparse python

# Generic parser function intialization in PYTHON
def create_parser(arguments):
    """Returns an instance of argparse.ArgumentParser"""
    # your code here
    parser = argparse.ArgumentParser(
        description="Description of your code")
    parser.add_argument("argument", help="mandatory or positional argument")
    parser.add_argument("-o", "--optional", 
    	help="Will take an optional argument after the flag")
    namespace = parser.parse_args(arguments)
    # Returns a namespace object with your arguments
    return namespace