Imports

Hello!
Just read this article: https://www.llamaindex.ai/blog/introducing-the-property-graph-index-a-powerful-new-way-to-build-knowledge-graphs-with-llms
I'm trying to use the low-level manipulation of data mentioned in the last part "Using the Property Graph Store"... but it uses two classes (EntityNode and Relation) that are not imported anywhere in the code... can you help me find it? 🙂
Thanks!