use std::rc::Rc;
use std::cell::{RefCell};

type VectorItemWrapper<T> = Rc<RefCell<T>>;

struct CustomIter<T> {
    i: usize,
    v: Vec<VectorItemWrapper<T>>,
}

impl<T> Iterator for CustomIter<T> {
    type Item = VectorItemWrapper<T>;

    fn next(&mut self) -> Option<VectorItemWrapper<T>> {
        if self.i == self.v.len() {
            None
        } else {
            self.i += 1;
            Some(self.v[self.i - 1].clone())
        }
    }
}