syntax_data: {"ast_node_type":"other","tokens":[{"end":80,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:     // Called when visiting a "node" candidate (with one or more subcandidates).
context_before:     visit_leaf: &mut impl FnMut(C, &mut T),
context_after:     // Returns an iterator over the candidate's children (by value or reference).