ociated with this action.

    - dest -- The name of the attribute to hold the created object(s)

    - nargs -- The number of command-line arguments that should be
        consumed. By default, one argument will be consumed and a single
        value will be produced.  Other values include:
            - N (an integer) consumes N arguments (and produces a list)
            - '?' consumes zero or one arguments
            - '*' consumes zero or more arguments (and produces a list)
            - '+' consumes one or more arguments (and produces a list)
        Note that the difference between the default and nargs=1 is that
        with the default, a single value will be produced, while with
        nargs=1, a list containing a single value will be produced.

    - const -- The value to be produced if the option is specified and the
        option uses an action that takes no values.

    - default -- The value to be produced if the option is not specified.

    - type -- A callable that accepts a single string argument, and
        returns the converted value.  The standard Python types str, int,
        float, and complex are useful examples of such callables.  If None,
        str is used.

    - choices -- A container of values that should be allowed. If not None,
        after a command-line argument has been converted to the appropriate
        type, an exception will be raised if it is not a member of this
        collection.

    - required -- True if the action must always be specified at the
        command line. This is only meaningful for optional command-line
        arguments.

    - help -- The help string describing the argument.

    - metavar -- The name to be used for the option's argument with the
        help string. If None, the 'dest' value will be used as the name.
Nc