$ cargo -q run --example demo --features="detect-color-support" thread 'main' panicked at examples/demo.rs:36:12: byte index 1 is not a char boundary; it is inside 'á' (bytes 0..2) of `áöù` note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace fn split (value: "áöù" , at: 1 ) at examples/demo.rs:35:16 fn rotate_left (value: "áöù" , mid: 1 ) at examples/demo.rs:29:16 fn collect_rotations (value: "áöù" ) at examples/demo.rs:22:16 fn app_logic (value.clone(): Wrapper ( "abc \n bcd" ), arr: [ 1 , 2 ], ... , flag: false ) at examples/demo.rs:14:16