syntax_data: {"ast_node_type":"function","tokens":[{"end":69,"kind":"keyword","start":0,"text":"fn"}]}
source_snippet:     fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
context_before:     /// span starts and ends in the same file, which is almost always the case.
context_after:         const TAG_VALID_SPAN: u8 = 0;