{"ast_node_type":"function","tokens":[{"end":59,"kind":"keyword","start":0,"text":"r\"fn"}]}
            r"fn f() { let res = 1 + (2 - 3) +$0 4 + 5; }",
            flip_binexpr,
            r"fn f() { let res = 1 + 4 + (2 - 3) + 5; }",