Possible bug at this line where str should be value in `"/" if "/" in str else "."`

[simkimsia]

Over in this line https://github.com/mariocesar/django-ltree/blob/154c7e31dc004a753c5f6387680464a23510a8ce/django_ltree/fields.py#L13

When i run python3.7 this doesn't seem to trigger any issue but when I upgrade to python3.8 in my django app, I get this error.

File "/usr/local/lib/python3.8/dist-packages/django_ltree/fields.py", line 13, in __init__
    split_by = "/" if "/" in str else "."
TypeError: argument of type 'type' is not iterable