Hello! Please make sure to check all these boxes before submitting a Pull Request
(PR). Once you have checked the boxes, feel free to remove all text except the
justification in point 6.

1. You have run tests on this submission locally with pytest (see example command in .github/workflows/testing.yml).
2. This submission is formatted and linted with ruff. Formatting & linting are done automatically if you have installed the .pre-commit-config.yaml properly in a local environment.
3. If this PR adds or updates the codebase, appropriate adjustments are made to corresponding docstrings and changes are covered (see (1.) above).
4. This pull request is directed to the pysal/main branch. This is important, as any PRs submitted against any other branches will be delayed.
5. You have assigned a
   reviewer and added relevant labels (if possible)
6. The justification for this PR is:
   This PR adds test coverage for the simport function to handle edge
   cases such as empty string and None inputs, improving robustness and
   preventing regressions.