xor logical operator

Library "xor"

xor(a, b)
  xor: Exclusive or, or exclusive disjunction is a logical operation that is true if and only if its arguments differ (one is true, the other is false).
  Parameters:
    a: first argument
    b: second argument
  Returns: returns xor (true only if a and b are true, but not both)

Example:

true xor true = false
true xor false = true
false xor true = true
false xor false = false