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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 set_swimlane(self, value):
 """Convert from list of dicts with values to list of values Cache list items with their ID pairs to restore existing IDs to unmodified values to prevent workflow evaluating on each save for any already existing values """

        value = value or []

        self._initial_value_to_ids_map = defaultdict(list)
        for item in value:
            self._initial_value_to_ids_map[item['value']].append(item['id'])

        return super(ListField, self).set_swimlane([d['value'] for d in value])