You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: naive.rs
    path of file: ./repos/Rust/src/general/permutations
    
    the code of the file until where you have to start completion: use std::collections::HashSet;
use std::fmt::Debug;
use std::hash::Hash;

/// Here's a basic (naive) implementa
    
pub fn permute_unique<T: Clone + Debug + Eq + Hash + Copy>(arr: &[T]) -> Vec<Vec<T>> {
    if arr.is_empty() {
        return vec![vec![]];
    }
    let n = arr.len();
    let count = (1..=n).product(); // n! permutations
    let mut collector = Vec::with_capacity(count); // collects the permuted arrays
    let mut arr = arr.to_owned(); // Heap's algorithm needs to mutate the array
    permute_recurse_unique(&mut arr, n, &mut collector);
    collector
}