operator ^ method
Combines this spec with another using XOR logic (^).
Returns a new spec that is satisfied when exactly one of this spec
or other is satisfied, but not both. Use this for mutually exclusive
conditions. Shorthand for calling xor.
Example:
// Exactly one must be true, not both
final exclusive = IsStudent() ^ IsWorking();
final status = IsActive() ^ IsArchived(); // Not both, one required
Implementation
Spec<T> operator ^(Spec<T> other) => _Xor(this, other);