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#[derive(PartialEq, Debug)]
pub struct Shoe {
    pub size: u32,
    pub style: String,
}

pub fn shoes_in_my_size(shoes: Vec<Shoe>, shoe_size: u32) -> Vec<Shoe> {
    shoes.into_iter()
        .filter(|s| s.size == shoe_size)
        .collect()
}


#[derive(Debug)]
pub struct Counter {
    count: u32,
}

impl Counter {
    pub fn new() -> Counter {
        Counter {
            count: 0,
        }
    }
}

impl Iterator for Counter {
    type Item = u32;

    fn next(&mut self) -> Option<Self::Item> {
        self.count += 1;
        
        if self.count < 6 {
            Some(self.count)
        } else {
            None
        }
    }
}