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### Description

[Description of the issue]
[Steps to reproduce]
[What did you expect to happen?  What happened?  All the time?]
[Are there any error messages printed to the console?]

### Versions

- Operating system: [here]
- `libfive` commit hash: [here]
  - Is this the latest commit to `master`?  [yes]
- Qt version (if applicable): [here]

### Additional Information

Any additional information, configuration or data that might be necessary to reproduce the issue.

### Common questions
[Delete this section if not relevant]

If this is a behavior issue, does the test suite (`libfive/test/libfive-test`) pass?

If this is a graphics issue on Linux, report the results of updating your graphics drivers (and switching to binary graphics drivers if applicable).

If there are error messages in the console, have you searched for them and followed up on any promising leads?
