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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 versionable_delete(self, instance, timestamp):
 """ Soft-deletes the instance, setting it's version_end_date to timestamp. Override this method to implement custom behaviour. :param Versionable instance: :param datetime timestamp: """

        instance._delete_at(timestamp, using=self.using)