[docs] A bug in documentation in argparse

[Xan]

Hi,

Just a comment, please put in argparse documentation that in 
add_argument we could not combine with success type and nargs='?'. For 
example:
parser.add_argument("-m", "--mostrar", nargs='+', type=int)

does not check if all elements in list (1 or more) are integers or not.

I don't know if it's a bug in argparse or if this behaviour is 
intentionally this way. In last case, please upgrade the documentation.

Thanks in advance,
Xan.