This member is added by an implicit conversion from Xor[Left, Right] to
any2stringadd[Xor[Left, Right]] performed by method any2stringadd in scala.Predef.
This member is added by an implicit conversion from Xor[Left, Right] to
StringFormat[Xor[Left, Right]] performed by method StringFormat in scala.Predef.
Proves either Left or Right but not both