Explain Python Immutability, Tuples, Hash Tables, and Caller-Level Errors

Discuss Python object immutability, tuple operations, dictionary internals, and exception handling for a small record-management class. ### Part 1 — Immutability and Tuple Operations Explain what an immutable object is. Starting with `items = (3,)`, explain the result of `items += (1, 2)` and what happens to another variable that previously referred to the original tuple. Compare tuple indexing, membership testing, and concatenation costs. Explain whether a tuple containing a list is deeply immutable. #### What This Part Should Cover Distinguish an object from a name bound to that object; explain tuple rebinding, shallow immutability, and operation-specific complexity. ### Part 2 — Hash Table Behavior Explain how a hash table supports inserting, finding, updating, and removing a dictionary entry. Discuss hashing, collisions, resizing, and expected versus worst-case costs. Explain the requirement for stable key hashing and equality. #### What This Part Should Cover Describe a plausible hash-table mechanism without claiming that all languages or Python implementations use one collision strategy. Include amortization and the cost of hashing the key itself. ### Part 3 — Handling Record-Operation Errors A class exposes insert, update, and remove methods. Explain when the methods should raise an error and how a caller can catch an expected failure around a method call. Discuss the effect of an exception on the stored data. #### What This Part Should Cover Separate operation invariants from caller recovery policy. Give a specific example of an expected error and explain why catching every error silently would be harmful. ### Constraints Use ordinary Python semantics. Assume tuple elements are object references; any stated constant-time key operation assumes bounded-cost hashing and equality. Duplicate-insert and missing-key behavior are API decisions to declare, not facts supplied by the scenario. ### Clarifying Questions - Should insertion overwrite an existing key, or reject it? - Should a missing record be an expected user error or an internal invariant violation? ```hint Follow the object identity A name can be rebound even when the object it used to reference cannot be modified. ``` ### What a Strong Answer Covers - Correct tuple semantics and operation-specific costs. - Collision handling, dictionary resizing, and stable hashable keys. - Caller-level handling of declared errors with preserved class invariants. ### Follow-up Questions - Why can a tuple containing a list be an invalid dictionary key? - How would you test that a failed update leaves the record store unchanged?