Function map_split::split4

pub fn split4<'a, K: 'a, V: 'a, S, SplitType>(v: &'a mut HashMap<K, V, S>) -> (HashMapA<'a, K, V, S, SplitType>, HashMapB<'a, K, V, S, SplitType>, HashMapC<'a, K, V, S, SplitType>, HashMapD<'a, K, V, S, SplitType>) where K: Eq + Hash, S: BuildHasher, V: Splittable4<'a, SplitType>

Splits a HashMap into 4 disjoint hashmap references, able to access the split parts of the stored Splittable4 values independently.