Importing is recommended rather than mandatory.
The recommendation is meant to keep the user in sync with the assumed state of the project at the beginning of each stage.
If you decide to continue working on the same project from stage to stage, then your project will probably accumulate minor discrepancies when compared to the tutorial (e.g. model names, package names, positioning of models in screenshots), which might make it difficult for the user to follow the tutorial as the application gathers complexity.
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