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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 dbg_repr(self):
 """ Debugging representation of this CallStack object. :return: Details of this CalLStack :rtype: str """


        stack = [ ]
        for i, frame in enumerate(self):
            s = "%d | %s -> %s, returning to %s" % (
                i,
                "None" if frame.call_site_addr is None else "%#x" % frame.call_site_addr,
                "None" if frame.func_addr is None else "%#x" % frame.func_addr,
                "None" if frame.return_target is None else "%#x" % frame.return_target,
            )
            stack.append(s)

        return "\n".join(stack)