SeExpr learning materials [request]

I was wonder if anyone has a good beginner tutorials (or any learning materials) on SeExpr.
So that I can gradually learn how to create my own patterns.

@amyspark I was told that maybe you have some materials you can share.

For reference only, someone told me that because of the lack of relevant information, it is recommended to look at the shader-related information first

I never explored it much but this was what I found last time I was on the topic