If celery is not available. We cannot import anything from octavious.paralalizer.celery because 'import celery'
https://github.com/metglobal/octavious/blob/master/octavious/parallelizer/celery.py#L3
in that file would give an import error.
Even though this verson would probably work, You might want to change this to 'import celery'  to show your intention more clearly.