syntax_data: {"ast_node_type":"variable","tokens":[{"end":52,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let args = args.collect::<Vec<_>>();
context_before:                 let (func_ty, func, args) = self.call_args();
context_after:                 write!(f, "({:?}: {:?})(", func, func_ty)?;