use rand::RngExt;
use std::iter;
pub fn generate_string(len: usize) -> String {
const CHARSET: &[u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
let mut rng = rand::rng();
let one_char = || CHARSET[rng.random_range(0..CHARSET.len())] as char;
iter::repeat_with(one_char).take(len).collect()
}