syntax_data: {"ast_node_type":"variable","tokens":[{"end":74,"kind":"keyword","start":0,"text":"if"}]}
source_snippet:         if let Some(val) = std::env::var_os("RUSTC_FORCE_RUSTC_VERSION") {
context_before:         // during testing.
context_after:             hasher.write(val.to_string_lossy().into_owned().as_bytes())