Fix tutorial usage of open_port

[grcevski]

Closes #518

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (3753eeb) 79.20% compared to head (84892aa) 79.08%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #523      +/-   ##
==========================================
- Coverage   79.20%   79.08%   -0.13%     
==========================================
  Files          69       69              
  Lines        5772     5772              
==========================================
- Hits         4572     4565       -7     
- Misses        977      982       +5     
- Partials      223      225       +2     

Flag	Coverage Δ
integration-test	67.66% <ø> (-0.16%)	⬇️
unittests	45.25% <ø> (ø)

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