Added pairwise iteration algorithms

[matheusfvesco]

Could you please add the hacktoberfest label to this PR, if possible, please?

Describe your change:

Added a pairwise iteration algorithm. It will iterate over any iterable, yielding tuples that represent (iterable[i],iterable[i+1]). Second implementation allows specifying a step size. This algorithm can be useful for various domains, like:

• Iterating over frames of a video to track objects;
• Comparing the current word with the next to try to predict the next word;
• Comparing codons of a genetic sequence.

Couldn't find any wikipedia articles for this algorithm.

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.
• All new algorithms include at least one URL that points to Wikipedia or another similar explanation.
• If this pull request resolves one or more open issues then the description above includes the issue number(s) with a closing keyword: "Fixes #ISSUE-NUMBER".

[matheusfvesco]

Need reviews, please!

[matheusfvesco]

@chriso345 need reviews, please!

[cclauss]

@priya-sundaram-dev, please review.

[priya-sundaram-dev]

Thanks for the PR, @matheusfvesco, and for your patience — I took a careful pass. 🙂

What works: the code is clean and the docstrings are genuinely nice. I checked out the branch and ran the doctests: 16 tests in 3 items, 16 passed / 0 failed on Python 3.12, and I spot-checked the dict/set/string cases by hand — all correct. The DIRECTORY.md diff (incl. the physics/hamiltonian.py line) is just the auto-generated sync, so no concern there.

A couple of things worth discussing before merge:

1. pairwise_iteration_tee is exactly itertools.pairwise (stdlib since 3.10, which this repo targets) — same tee + offset recipe. We usually avoid re-implementing the stdlib. Two good options: (a) drop this function, or (b) keep it but reframe the docstring as "educational: here's how itertools.pairwise works under the hood" and cross-reference it, so a reader knows to prefer the builtin in real code.

2. pairwise_iteration_comprehension's step is the part that adds real value — the stdlib has no strided variant, so this is the function worth keeping. One note: items = [item for i, item in enumerate(iterable) if i % step == 0] materializes the whole input into a list, so the "iterator" laziness is lost for large inputs. That's fine for the educational scope, but a one-line comment saying so (or naming it strided_pairwise) would set expectations.

3. Nit: both docstrings say "Yields", but both return zip(...) rather than yield — worth changing to "Returns" for accuracy.

None of these are hard blockers; if you fold #1 and #2 in, I think this is in good shape. Nice work! 👍

[cclauss]

Nice review! I love yielding (just-in-time -- stream-flow delivery of) data to the caller.