Update docstrings and annotations in formulary length calculations - #2356

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Codecov Report

All modified lines are covered by tests ✅

Comparison is base (99f905b) 98.35% compared to head (91270f0) 98.35%.
Report is 1 commits behind head on main.

@@           Coverage Diff           @@
##             main    #2356   +/-   ##
=======================================
  Coverage   98.35%   98.35%           
=======================================
  Files         101      101           
  Lines        8580     8582    +2     
=======================================
+ Hits         8439     8441    +2     
  Misses        141      141           

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