- Replaced `range(len(scores))` with `enumerate(scores)` and used index (`i`) and `score` directly.

	- Removed need for `else` by appending to `results` once, then conditionally updating appended value given `return_documents`.

	- Used parameter name to match other kwarg usage.

	- Updated dictionary unioning to use Python 3.8 compatible syntax in :method:`CrossEncoder.rank`.

modified:   tests/test_cross_encoder.py
	- Parametrized test :callable:`test_rank` with checks for `return_documents` argument.

	- Used a `FixtureRequest` to do further testing when `return_documents` is True.

	- Changed method of unioning dictionary to `update` in :method:`CrossEncoder.rank` to avoid unpacking original dictionary.