fun logicOperations ← void by logic a, logic b
  writeLine("[ input values are " + a + ", " + b + " ]")
  writeLine("a and b: " + (a and b))
  writeLine(" a or b: " + (a or b))
  writeLine("  not a: " + (not a))
end
logicOperations(false, false)
logicOperations(false, true)
logicOperations(true, false)
logicOperations(true, true)