chore: add tests and small fixes in utils.py (#2554)
Linting and typing fixes, and add tests to improve test coverage in
utils.py
On the main branch, run `coverage run -m pytest
test_unstructured/test_utils.py` and then `coverage report -m
unstructured/utils.py` to see test coverage for `utils.py`. Check out to
this branch and do the same. The percent coverage should increase to 88%
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Co-authored-by: David Potter <potterdavidm@gmail.com>
