syntax_data: {"ast_node_type":"variable","tokens":[{"end":64,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let no_clean = env::var_os(&*ENV_NO_CLEAN_CFLAGS).is_some();
context_before:     // known to be possibly-harmful.
context_after:     if no_clean || target_env_is("msvc") {