syntax_data: {"ast_node_type":"variable","tokens":[{"end":94,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                             let variant = layout_of_variant(idx, Some(tag_encoding.clone()))?;
context_before:                         |variants, (idx, _discriminant)| {
context_after:                             Result::<Self, Err>::Ok(variants.or(variant))