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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 rollback(self, verbose=False):
 """ Remove classes and instances from the underlying repository, that have been created in the local repository of this class. Limitation: At this point, only classes and instances will be removed, but not qualifiers. """

        for ns, insts in self.instances.items():
            insts.reverse()
            for inst in insts:
                try:
                    if verbose:
                        print(_format("Deleting instance {0}", inst.path))
                    self.conn.DeleteInstance(inst.path)
                except CIMError as ce:
                    print(_format("Error deleting instance {0}", inst.path))
                    print(_format("     {0} {1}",
                                  ce.status_code, ce.status_description))
        for ns, cnames in self.class_names.items():
            self.default_namespace = ns
            cnames.reverse()
            for cname in cnames:
                try:
                    if verbose:
                        print(_format("Deleting class {0!A}:{1!A}",
                                      ns, cname))
                    self.conn.DeleteClass(cname)
                except CIMError as ce:
                    print(_format("Error deleting class {0!A}:{1!A}",
                                  ns, cname))
                    print(_format("     {0} {1}",
                                  ce.status_code, ce.status_description))