added TODO: Tree Observation needs to be adjusted to new transition possibilities.

1 job for master in 1 minute and 48 seconds (queued for 6 seconds)
Name Stage Failure
tests Test
coverage html
python -c "$BROWSER_PYSCRIPT" htmlcov/index.html
___________________________________ summary ____________________________________
py36: commands succeeded
py37: commands succeeded
ERROR: flake8: commands failed
docs: commands succeeded
coverage: commands succeeded
ERROR: Job failed: command terminated with exit code 1