Crate xref

Enums

XRef	Kind of like Cow, but might also be a Ref (from a RefCell) Also, does not use ToOwned. This is because the main point of an XRef is not to Copy On Write, but to either hold an owned value or a reference to a value
XRefMut	Kind of like Cow, but might also be a RefMut (from a RefCell) Also, does not use ToOwned. This is because the main point of an XRefMut is not to Copy On Write, but to either hold an owned value or a reference to a value