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use std::slice;

pub struct Iter<'a, T: 'a> {
    item: Option<(&'a T, slice::Iter<'a, T>)>,
    is_first: bool,
}

impl<'a, T> Iter<'a, T> {
    pub fn with(item: Option<(&'a T, slice::Iter<'a, T>)>) -> Iter<'a, T> {
        Iter {
            item: item,
            is_first: true,
        }
    }
}


impl<'a, T> Iterator for Iter<'a, T> {
    type Item = &'a T;

    fn next(&mut self) -> Option<&'a T> {
        match &mut self.item {
            &mut None => None,
            &mut Some((ref first, ref mut vec)) => {
                if self.is_first {
                    self.is_first = false;
                    Some(first)
                } else {
                    vec.next()
                }
            }
        }
    }
}