UPair.

This data structure permits to have unordered pair keys for Hash based storage for example.

Basic requirements.

The inner Type needs to implement the Ord trait.

let storage = HashSet::new();
storage.insert(UPair::new(1, 2));
assert!(storage.contains(UPair::new(2, 1));

Trait implemented.

• Debug if implemented by inner type.
• Copy if implemented by inner type.
• Hash if implemented by inner type.
• Eq, PartialEq if implemented by inner type.
• Ord, PartialOrd.
• From<(T, T)>.
• From<[T; 2]>.
• IntoIterator.