Argparse Unable to access optional argument with specific name

Question

The Problem is that argparse can't recognize the argument with tags like --argument-option
Example code

import argparse

parser = argparse.ArgumentParser(description="Help")
parser.add_argument("-a", "--argument-option", metavar="", help="Help")
args = parser.parse_args()
option = args.argument-option
print(option)

Results in AttributeError: 'Namespace' object has no attribute 'argument'

I tried few codes and was able to find a solution by changing -a to --a :-

import argparse

parser = argparse.ArgumentParser(description="Help")
parser.add_argument("--a", "--argument-option", metavar="", help="")   # change here
args = parser.parse_args()
option = args.a                # And here
print(option)

But if possible i would like to shorten the optional argument --argument-option to older -a and not --a