Question
Build utilities for converting between stack observations and call events. Stack frames are ordered outermost to innermost. ```python def stacks_from_events(events: list[str]) -> list[tuple[tuple[str, ...], int]]: ... def convert_samples_to_events(samples: list[dict]) -> list[dict]: ... def convert_confirmed_samples_to_events(samples: list[dict], consecutive: int) -> list[dict]: ... ``` For an event stream, push on `enter`/`start`, pop on `exit`/`end`, record the stack after each event, and run-length encode adjacent identical stacks. For sampled stacks, compare adjacent samples using their longest common prefix. Emit removed frames as `end` events from innermost outward, then emit added frames as `start` events from outermost inward. Use the new sample's timestamp and leave frames in the final sample open. Samples have `ts` and `stack` fields; events emitted from samples have `name`, `kind` (`start` or `end`) and `ts`. Input event strings use `enter name`, `exit name`, or `name:start:timestamp` / `name:end:timestamp`. Ignore event timestamps for stack snapshot counting. Reject an exit that does not match the current innermost frame with `ValueError`; leave unmatched active entries open at EOF. For confirmed conversion, accept a candidate stack only on its Nth consecutive occurrence, using that sample's timestamp. A different sample resets the candidate streak; returning to the confirmed stack clears it. An unconfirmed candidate at EOF emits nothing. N must be a positive integer. All three functions belong to the base contract and public cases. Reject unsupported event kinds, missing names or missing colon-format timestamps with `ValueError`. Names do not contain colons; timestamp text is nonempty and opaque because this conversion does not use it. Confirmation counts reject booleans and nonintegers. ## Requirements and edge cases - Treat the same function name at different depths as distinct invocations. - Identical samples emit nothing; an empty sample closes the previous stack. - Reject malformed exits; do not silently pop an unrelated frame. - Preserve input order and timestamps. ## Implementation approach 1. Implement both base conversions. 2. Accept a stack change only after it appears in `N` consecutive samples. ## Design discussion (not graded) - Stream the conversion without retaining the entire input. - Explore suffix-based matching when only leaf-side frames are visible, and state the ambiguity this creates. - Filter short-lived calls using either elapsed time or sample count.