Tutorial: Fix file path, typos, reformat Python

[sglavoie]

Hey there! I hope you'll find those changes useful. I was following the tutorial and spotted a few things that would need to be updated. I will be adding comments to the pull request to explain my reasoning behind the changes. :slightly_smiling_face:

[coveralls]

Pull Request Test Coverage Report for Build 451

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 85.052%

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Totals
Change from base Build 446:	0.0%
Covered Lines:	1707
Relevant Lines:	2007

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💛 - Coveralls