"""Pagination helper — contains an off-by-one bug that drops the last item of a page.

The bug: `end = start + size - 1` and slicing `items[start:end]` excludes the last
element of each page. A correct implementation returns exactly `size` items per page
(and the remainder on the final page).
"""


def paginate(items, page, size):
    """Return the `page`-th (1-indexed) slice of `items` with `size` per page."""
    start = (page - 1) * size
    end = start + size - 1  # BUG: off-by-one — drops the last item of the page
    return items[start:end]