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 ```
 
 NOTE: This is not an officially supported Google product.
+
+
+## How to debug the expanded derive macro for `argh`
+
+The `argh::FromArgs` derive macro can be debugged with the [cargo-expand](https://crates.io/crates/cargo-expand) crate.
+
+### Expand the derive macro in `examples/simple_example.rs`
+
+See [argh/examples/simple_example.rs](./argh/examples/simple_example.rs) for the example struct we wish to expand.
+
+First, install `cargo-expand` by running `cargo install cargo-expand`. Note this requires the nightly build of Rust.
+
+Once installed, run `cargo expand` with in the `argh` package and you can see the expanded code.