Changing Init files and tutorials

[devendragovil]

I have made the following changes:

1. Changed init files to get models in the namespace of the base package
2. Changed tutorials to reflect the new change

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.41%. Comparing base (80275bb) to head (b6c9e29).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #297      +/-   ##
==========================================
+ Coverage   97.37%   97.41%   +0.03%     
==========================================
  Files          58       58              
  Lines        2059     2087      +28     
==========================================
+ Hits         2005     2033      +28     
  Misses         54       54              

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[devendragovil]

@mhajij Please review

[ffl096]

Please fix the ruff error, then this is ready to be merged.