Update features_extract.py

[codecov[bot]]

Codecov Report

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

Project coverage is 48.38%. Comparing base (a98e887) to head (32b3186).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #58 +/- ## ======================================= Coverage 48.38% 48.38% ======================================= Files 8 8 Lines 465 465 ======================================= Hits 225 225 Misses 240 240 ``` | [Flag](https://app.codecov.io/gh/SupervisedStylometry/SuperStyl/pull/58/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=SupervisedStylometry) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/SupervisedStylometry/SuperStyl/pull/58/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=SupervisedStylometry) | `48.38% <0.00%> (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=SupervisedStylometry#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.