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What is a generator expression, and how does it differ syntactically and behaviorally from a list comprehension? How do you write a nested comprehension, like flattening a list of lists into a single flat list? How do you send a value INTO a generator using the .send() method, and how does this differ from just calling next()? How does 'yield from' delegate iteration to a sub-generator, and what does it return as its own expression value? How does lazy evaluation in a chained sequence of generator expressions actually process elements, one at a time end-to-end, without intermediate lists? How would you implement a memory-efficient sliding window or batching generator over a large iterable? How do you correctly close a generator early and ensure any try/finally cleanup inside it still runs? How would you implement a coroutine-style generator-based pipeline (the classic pre-async/await pattern) using multiple chained 'send()'-driven generators? How do you write a comprehension with MULTIPLE 'if' conditions, and how does that differ from combining them with 'and'? How would you profile whether a generator expression is actually providing a measurable memory or performance benefit over a list comprehension in a specific use case?
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How does generator.throw() let you inject an exception into a paused generator, and how would the generator handle it?

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Answer

generator.throw(exception) resumes the generator by raising the given exception at the currently-paused yield point INSIDE the generator's frame — if the generator has a try/except around that yield, it can catch and handle it (potentially yielding a different value); otherwise, the exception propagates out to the caller of throw().
def resilient_gen():
    try:
        while True:
            yield "working"
    except ValueError:
        yield "recovered from error"

gen = resilient_gen()
next(gen)                      # "working"
print(gen.throw(ValueError))   # "recovered from error"
Real-world example Building a generator-based state machine or task runner that can gracefully handle externally-injected error conditions.

Common follow-ups: What does generator.close() do differently from throw(), in terms of what exception it raises internally?

Exception Handling
All 15 Comprehensions & Generators questions