Simple queries not working

[Remorax]

Hi,

The search query described here, for finding all is_a relationships do not work, even for the provided example.

I followed all the examples given, loaded the pizza ontology but on trying the search query, I get the following error:
Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/local/lib/python3.6/site-packages/owlready2/namespace.py", line 191, in search v2 = [child.storid for child in v.descendants()] AttributeError: 'str' object has no attribute 'descendants'

Can someone please help me out?