syntax_data: {"ast_node_type":"other","tokens":[{"end":70,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:                 // If there are no alternatives, return `Uninhabited`.
context_before:                 let mut alts = alts.into_iter().map(Self::from_tree).filter_map(Result::ok);
context_after:                 let dfa = alts.next().ok_or(Uninhabited)?;