pub fn main(world: World) -> Void raises {
    let text: String = "zero"
    let all: Span<u8> = std.mem.span(text)
    let middle: Span<u8> = text[1..3]
    let expected: Span<u8> = std.mem.span("er")
    if std.mem.len(text) == 4 && std.mem.len(all) == 4 && text[0] == 122 && std.mem.eqlBytes(middle, expected) {
        check world.out.write("string byte ergonomics ok\n")
    }
}