syntax_data: {"ast_node_type":"variable","tokens":[{"end":86,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:             let (discr_did, discr_offset) = adt_def.discriminant_def_for_variant(idx);
context_before:             let idx = adt_def.variant_index_with_ctor_id(variant_ctor_id);