syntax_data: {"ast_node_type":"function","tokens":[{"end":94,"kind":"keyword","start":0,"text":"fn"}]}
source_snippet:     fn diverge_cleanup_target(&mut self, target_scope: region::Scope, span: Span) -> DropIdx {
context_before:     /// the program breaks out of a if-then scope.
context_after:         let target = self.scopes.scope_index(target_scope, span);