Add a feature for compare.

Cargo.toml

@@ -8,7 +8,6 @@ license = "0BSD"
 name = "toy"
 path = "src/main.rs"
 
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
 nom = "7.1.1"
@@ -19,3 +18,5 @@ tracing-opentelemetry = "0.17.2"
 tracing-subscriber = {version="0.3.16", features=["env-filter"]}
 
 [features]
+default = ["compare"]
+compare = []