Upgrade to FunctionImplementations v0.4

[mtfishman]

Closes #47.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 64.28%. Comparing base (cbba3e4) to head (036e41c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #48   +/-   ##
=======================================
  Coverage   64.28%   64.28%           
=======================================
  Files          21       21           
  Lines         728      728           
=======================================
  Hits          468      468           
  Misses        260      260           

Flag	Coverage Δ
docs	0.00% <ø> (ø)

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