{"ast_node_type":"other","tokens":[{"end":78,"kind":"keyword","start":0,"text":"Op::Subtree"}]}
            Op::Subtree { tokens, .. } => collect_vars(collector_fun, tokens),
            Op::Var { name, .. } => collector_fun(name.clone()),
            Op::Repeat { tokens, .. } => collect_vars(collector_fun, tokens),