syntax_data: {"ast_node_type":"variable","tokens":[{"end":47,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let hash = if *self == ExpnId::root() {
context_before:         assert_default_hashing_controls(ctx, "ExpnId");
context_after:             // Avoid fetching TLS storage for a trivial often-used value.