Local testing fails
I managed to reproduce. This comes from the CodeType init signature that is different in python 3.8.8
I opened a PR to fix this test
Thanks !
I'm following the CI setup as described in 

https://github.com/huggingface/datasets/blob/8eee4fa9e133fe873a7993ba746d32ca2b687551/.circleci/config.yml#L16-L19

in a new conda environment, at commit https://github.com/huggingface/datasets/commit/4de6dbf84e93dad97e1000120d6628c88954e5d4

and getting

```
FAILED tests/test_caching.py::RecurseDumpTest::test_dump_ipython_function - TypeError: an integer is required (got type bytes)
1 failed, 2321 passed, 5109 skipped, 10 warnings in 124.32s (0:02:04)
```

Seems like a discrepancy with CI, perhaps a lib version that's not controlled? 
Tried with `pyarrow=={1.0.0,0.17.1,2.0.0}`
Local testing fails 
 I'm following the CI setup as described in 

https://github.com/huggingface/datasets/blob/8eee4fa9e133fe873a7993ba746d32ca2b687551/.circleci/config.yml#L16-L19

in a new conda environment, at commit https://github.com/huggingface/datasets/commit/4de6dbf84e93dad97e1000120d6628c88954e5d4

and getting

```
FAILED tests/test_caching.py::RecurseDumpTest::test_dump_ipython_function - TypeError: an integer is required (got type bytes)
1 failed, 2321 passed, 5109 skipped, 10 warnings in 124.32s (0:02:04)
```

Seems like a discrepancy with CI, perhaps a lib version that's not controlled? 
Tried with `pyarrow=={1.0.0,0.17.1,2.0.0}` 
 I managed to reproduce. This comes from the CodeType init signature that is different in python 3.8.8
I opened a PR to fix this test
Thanks !