syntax_data: {"ast_node_type":"variable","tokens":[{"end":47,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let prefix = env::var_os(&*ENV_LLVM_PREFIX)
context_before: fn locate_llvm_config() -> Option<PathBuf> {
context_after:         .map(|p| PathBuf::from(p).join("bin"))