fix #303

[d-chambers]

Description

fixes #303

Checklist

I have (if applicable):

• [x] referenced the GitHub issue this PR closes.
• [x] documented the new feature with docstrings or appropriate doc page.
• [x] included a test. See testing guidelines.
• [x] your name has been added to the contributors page (docs/contributors.md).
• [x] added the "ready_for_review" tag once the PR is ready to be reviewed.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (9a4e0c3) 99.29% compared to head (d22cca5) 99.29%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #304 +/- ## ======================================= Coverage 99.29% 99.29% ======================================= Files 84 84 Lines 6714 6714 ======================================= Hits 6667 6667 Misses 47 47 ``` | [Flag](https://app.codecov.io/gh/DASDAE/dascore/pull/304/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=DASDAE) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/DASDAE/dascore/pull/304/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=DASDAE) | `99.29% <100.00%> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=DASDAE#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.