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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add_argument(self, dest, nargs=1, obj=None):
 """Adds a positional argument named `dest` to the parser. The `obj` can be used to identify the option in the order list that is returned from the parser. """

        if obj is None:
            obj = dest
        self._args.append(Argument(dest=dest, nargs=nargs, obj=obj))