DO NOT MERGE - just a doctest check

[pavoljuhas]

DO NOT MERGE

• Copy PR 7354
• Introduce intentional failure at new doctests

[pavoljuhas]

Good, the doctest fails for this PR as intended at https://github.com/quantumlib/Cirq/actions/runs/17993765487/job/51189030096?pr=7668

This means new contrib code in #7354 is covered by doctests.

[pavoljuhas]

CI check completed. Closing.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.37%. Comparing base (63cfe53) to head (e667d13).

Additional details and impacted files

@@           Coverage Diff            @@
##             main    #7668    +/-   ##
========================================
  Coverage   99.37%   99.37%            
========================================
  Files        1082     1087     +5     
  Lines       96691    97188   +497     
========================================
+ Hits        96086    96583   +497     
  Misses        605      605            

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