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As a large system with generic operations evolves, new types of data objects or new operations may be needed. For each of the three strategies — generic operations with explicit dispatch, data-directed style, and message-passing-style — describe the changes that must be made to a system in order to add new types or new operations. Which organization would be most appropriate for a system in which new types must often be added? Which would be most appropriate for a system in which new operations must often be added?