use rand::distributions::{Distribution, Standard}; use rand::prelude::*; use rand::rngs::StdRng; pub fn vec(size: usize, start: usize) -> Option> where Standard: Distribution, { if size > start + 2 { let mut rng = StdRng::from_entropy(); Some((0..size).map(|_| rng.gen()).collect()) } else { None } }