assert prop.clean(...) doesn't test well enough since clean() methods on this branch produce 2-tuples, and you should test what's in the tuple, not just that it returned something non-empty. So I fixed it in several places to test the tuple contents.  | 
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|---|---|---|
| .. | ||
| v20 | ||
| v21 | ||
| __init__.py | ||
| test_pattern_equivalence.py | ||
| test_properties.py | ||
| test_spec_version_detect.py | ||
| test_utils_type_checks.py | ||
| test_workbench.py | ||