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How do you create a custom exception class, and what's the minimal amount of code needed? What is the difference between 'raise' and 'raise ... from ...' for exception chaining? How do you access details about the exception currently being handled, like its type, value, and traceback, using sys.exc_info()? How does the 'else' clause on a try statement work, and what's its purpose compared to just putting that code at the end of 'try'? How would you design a custom exception HIERARCHY for an application, and why does this matter for how callers can catch errors at different granularities? How does context manager __exit__ interact with exception handling, and how can it SUPPRESS an exception by returning True? How would you implement a retry-with-backoff decorator that catches specific transient exceptions and retries with increasing delays? How does exception performance (raising/catching) compare to normal control flow, and why does Python's EAFP style still encourage using exceptions for routine control flow, unlike some other languages? How would you write a context manager using @contextlib.contextmanager that both sets up a resource AND properly handles/logs any exception that occurs while it's in use? How would you implement a circuit breaker pattern using exception handling, to stop repeatedly calling a service that's consistently failing?
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How does Python 3.11's exception groups (ExceptionGroup) and the 'except*' syntax let you handle MULTIPLE unrelated exceptions raised together?

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Answer

ExceptionGroup wraps multiple exceptions raised together (common in concurrent code, like asyncio.gather with multiple failures) as a single object; 'except*' matches and handles the SUBSET of exceptions within the group matching a given type, potentially re-raising a NEW ExceptionGroup with the remaining unmatched ones.
try:
    raise ExceptionGroup("multiple failures", [ValueError("bad value"), TypeError("bad type")])
except* ValueError as eg:
    print(f"Handled ValueErrors: {eg.exceptions}")
except* TypeError as eg:
    print(f"Handled TypeErrors: {eg.exceptions}")
Real-world example Handling multiple independent failures from concurrent tasks (like several parallel API calls) that fail simultaneously with different exception types.

Common follow-ups: How does asyncio.gather() (or TaskGroup in 3.11+) actually produce an ExceptionGroup from multiple failed concurrent tasks?

Concurrency (asyncio/threading/multiprocessing)
All 15 Exception Handling questions