Iterator protocol class

Build a custom iterator class that lazily yields squared values until a stop value.

iterator-protocol class lazy-evaluation stop-value

Create a class named `SquareIterator` that implements the iterator protocol (i.e., has `__iter__` and `__next__` methods).

When instantiated with an integer argument `stop`, an instance should produce a lazy sequence of squares: `0², 1², 2², ..., n²` where `n` is the largest integer such that `n² < stop`. The sequence stops before reaching or exceeding the value of `stop`.

Your class must:
- Accept exactly one positional argument `stop` (an integer).
- Be an iterable (so `iter(obj)` returns the object).
- Be an iterator (so `next(obj)` works).
- Raise `StopIteration` automatically when the sequence is exhausted.

You may assume `stop` is a non-negative integer.

Implement the `SquareIterator` class with the required methods.

Constraints

- `0 <= stop <= 10**6`
- Must not use generator functions or `yield` in the class implementation.
- Must be memory-efficient: do not precompute the entire list of squares.

Example

>>> obj = SquareIterator(5)
>>> list(obj)
[0, 1, 4]
>>> obj = SquareIterator(1)
>>> list(obj)
[0]
>>> obj = SquareIterator(0)
>>> list(obj)
[]

10 points ~10 min

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Hints

Track the current integer with an internal attribute, starting at 0.

In `__next__`, compute the square and compare it to `stop`; raise `StopIteration` when the square is no longer less than `stop`.

Remember that `__iter__` should return `self`.

Test Results

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