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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 clear_instances(self, instances=None):
 """Request to "remove" the given instances list or all if not provided :param instances: instances to remove (all instances are removed if None) :type instances: :return: None """

        if instances is None:
            instances = self.instances[:]  # have to make a copy of the list
        for instance in instances:
            self.remove_instance(instance)