Extending @formula syntax is difficult to understand

[yanyu2015]

Extending @formula syntax is difficult to understand.
I read the examples of ploy in the official documentation, but I feel that the comments are not detailed enough, and I still don't quite understand.
For example, why define StatsModels.apply_schema, and after defining it, how is it called in f = apply_schema(f, schema(data)) ? Can you give a detailed and clear procedure?

[kleinschmidt]

Dear @yanyu2015, issues are really only meant for reporting bugs, requesting features, etc.

For support requests like this, please use https://discourse.julialang.org/, the julia slack https://julialang.org/slack/, or another community forum https://julialang.org/community/!