syntax_data: {"ast_node_type":"other","tokens":[{"end":51,"kind":"keyword","start":0,"text":"Box::new(AggregateKind::Tuple),"}]}
source_snippet:                     Box::new(AggregateKind::Tuple),
context_before:                 Rvalue::Aggregate(
context_after:                     fields.iter().map(|e| self.parse_operand(*e)).collect::<Result<_, _>>()?