feat: make momentum-ness infectious

[Saransh-cpp]

Description

Kindly take a look at CONTRIBUTING.md.

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Checklist

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Before Merging

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.27%. Comparing base (a6b0731) to head (872d22b).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #437      +/-   ##
==========================================
+ Coverage   86.13%   86.27%   +0.14%     
==========================================
  Files          96       96              
  Lines       11132    11139       +7     
==========================================
+ Hits         9588     9610      +22     
+ Misses       1544     1529      -15     

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[Saransh-cpp]

I tried doing this without creating MomentumClass, but that introduced a lot of edge cases and if conditions in the _flavor_of function. Using MomentumClass makes it clean and uniform for all the backends.

[jpivarski]

This looks good to me! I think you can merge this.