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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 arg(self, state, index, stack_base=None):
 """ Returns a bitvector expression representing the nth argument of a function. `stack_base` is an optional pointer to the top of the stack at the function start. If it is not specified, use the current stack pointer. WARNING: this assumes that none of the arguments are floating-point and they're all single-word-sized, unless you've customized this CC. """

        session = self.arg_session
        if self.args is None:
            arg_loc = [session.next_arg(False) for _ in range(index + 1)][-1]
        else:
            arg_loc = self.args[index]

        return arg_loc.get_value(state, stack_base=stack_base)