syntax_data: {"ast_node_type":"function","tokens":[{"end":66,"kind":"keyword","start":0,"text":"pub"}]}
source_snippet:     pub fn merge(&self, mut spans: FxHashMap<Symbol, Vec<Span>>) {
context_before:     /// Prepend the given set of `spans` onto the set in `self`.
context_after:         let mut inner = self.spans.borrow_mut();