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Also, there are a lot of uses of macro_rules! in the Rust compiler and standard library repository.

https://github.com/rust-lang/rust/search?q=macro_rules&type=

Looking at some of those and reading https://doc.rust-lang.org/rust-by-example/macros/syntax.html and https://doc.rust-lang.org/reference/macros-by-example.html can potentially be instructive.