Python argparse: Make at least one argument required

args = vars(parser.parse_args())
if not any(args.values()):
    parser.error('No arguments provided.')

if not (args.process or args.upload):
    parser.error('No action requested, add -process or -upload')

I know this is old as dirt, but the way to require one option but forbid more than one (XOR) is like this:

parser = argparse.ArgumentParser()
group = parser.add_mutually_exclusive_group(required=True)
group.add_argument('-process', action='store_true')
group.add_argument('-upload',  action='store_true')
args = parser.parse_args()
print args

Output:

>opt.py  
usage: multiplot.py [-h] (-process | -upload)  
multiplot.py: error: one of the arguments -process -upload is required  

>opt.py -upload  
Namespace(process=False, upload=True)  

>opt.py -process  
Namespace(process=True, upload=False)  

>opt.py -upload -process  
usage: multiplot.py [-h] (-process | -upload)  
multiplot.py: error: argument -process: not allowed with argument -upload