{"ast_node_type":"variable","tokens":[{"end":54,"kind":"keyword","start":0,"text":"let"}]}
                let ty_usize = self.cx.ty_path(usize);
                let usize = self.cx.path_ident(self.span, Ident::new(sym::usize, self.span));
                args.push(self.cx.param(self.span, size, ty_usize.clone()));