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How do context manager magic methods __enter__ and __exit__ work, and what does __exit__'s return value control? What is the difference between __new__ and __init__, and when would you override __new__? How do __iadd__ and other in-place operator methods (__isub__, __imul__) differ from their non-in-place counterparts? How does __bool__ (or the legacy __nonzero__) determine an object's truthiness, and what's the fallback if it's not defined?
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How does __slots__ interact with magic methods and instance attribute storage?

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Answer

__slots__ declares a fixed set of attribute names, replacing the per-instance __dict__ with more memory-efficient fixed-size slots and preventing arbitrary new attributes from being set. It doesn't itself define magic methods, but it affects ones related to attribute storage: __getattr__/__setattr__ still work as fallbacks, but pickling, copying, and cached_property require special handling since there's no __dict__ to store extra state.
class Point:
    __slots__ = ('x', 'y')
    def __init__(self, x, y):
        self.x, self.y = x, y

p = Point(1, 2)
try:
    p.z = 3  # AttributeError: no __dict__, z not in __slots__
except AttributeError as e:
    print(e)
Real-world example A high-volume data processing pipeline creating millions of small Point objects uses __slots__ to cut per-instance memory overhead significantly compared to default __dict__-based instances.

Common follow-ups: How does __slots__ interact with inheritance from a class without __slots__?;Why can't you use cached_property with __slots__ directly?

Memory Management & Garbage Collection;Descriptors & Properties
All 15 Magic Methods & Operator Overloading questions