syntax_data: {"ast_node_type":"variable","tokens":[{"end":92,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let mut alts = alts.into_iter().map(Self::from_tree).filter_map(Result::ok);
context_before:                 // Convert and filter the inhabited alternatives.
context_after:                 // If there are no alternatives, return `Uninhabited`.