This ticket's patch appears to have already been merged, yet it is open? 

On 2.7.9 docs [1], it has the exact language. The tutorial page [2] has a nice description as well. Finding this ticket really helped me understand argparse a bit better, and now I vote to close :).
AnneTheAgile, inspired by CodeTriage

1.[] ; ; ; ; ; ; ; ; ; ;  X.15.4. argparse — Parser for command-line options, arguments and sub-commands — Python 2.7.9 documentation
https://docs.python.org/2/library
action - The basic type of action to be taken when this argument is encountered at the command line.

2.[] ; ; ; ; ; ; ; ; ; ;  X.Argparse Tutorial — Python 2.7.9 documentation
https://docs.python.org/2/howto/argparse.html
we now specify a new keyword, action, and give it the value "store_true". This means that, if the option is specified, assign the value True to args.verbose. Not specifying it implies False.

3.[] ; ;List of all types of 'action', including customizable ; ; ; ; ; ; ; ;  X.15.4. argparse — Parser for command-line options, arguments and sub-commands — Python 2.7.9 documentation
https://docs.python.org/2/library/argparse.html#action
action="store_true"
action='store_false'
action="count"
action='store_const'
action='append'
action='version'
action=CustomFooAction