Fix import statement in DatasetOrTimetable example

[steffidlf]

Fix import statement for DatasetOrTimetable example

I could unfortunately find no corresponding issue but when following the documentation over here, I noticed that the import statement is incorrect.

This PR would fix it.

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[boring-cyborg]

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[boring-cyborg]

Awesome work, congrats on your first merged pull request! You are invited to check our Issue Tracker for additional contributions.