Composite Model - Add function return in output

[teubert]

Add returns of composite model function members to composite model output.

[github-actions]

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (ec48258) 83.29% compared to head (ec48258) 83.29%.

❗ Current head ec48258 differs from pull request most recent head a367143. Consider uploading reports for the commit a367143 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##              dev     #139   +/-   ##
=======================================
  Coverage   83.29%   83.29%           
=======================================
  Files         100      100           
  Lines       10507    10507           
=======================================
  Hits         8752     8752           
  Misses       1755     1755           

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