How to fix ModuleNotFoundError: No module named 'traitlets'

ModuleNotFoundError: No module named 'traitlets'
Recommended: Install via pip into your active environment.
python -m pip install traitlets

Verification

Command
python -c "import traitlets; print(traitlets.__version__)"
Expected output
Success! traitlets version x.y.z (e.g., 2.4.0)