Add HashMap::get_pair?

[SimonSapin]

HashMap has this method:

    pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&V>
        where K: Borrow<Q>, Q: Hash + Eq
    {
        self.search(k).map(|bucket| bucket.into_refs().1)
    }

I’d like to add this one, where the only difference is removing .1:

    pub fn get_pair<Q: ?Sized>(&self, k: &Q) -> Option<(&K, &V)>
        where K: Borrow<Q>, Q: Hash + Eq
    {
        self.search(k).map(|bucket| bucket.into_refs())
    }

This can be useful when K is &'a T where 'a is a longer lifetime than in Q.

Is this too obscure to pull its weight in std?

CC @gankro

[apasel422]

This is rust-lang/rfcs#1194.

[SimonSapin]

Indeed, thanks!