For sets S and T , the syntax S ˆ T returns a new set that is the symmetric difference, that is, a set of elements that are in precisely one of S or T . This syntax is supported by the special xor...

difference, that is, a set of elements that are in precisely one of
S
or

T. This syntax is supported by the special xor method. Provide an

implementation of that method in the context of the MutableSet abstract

base class, relying only on the five primary abstract methods of that class.