x = 1, y = 2, z = 3
x = 1, y = 2, z = 3
x = 1, y = 3, z = null
x = 1, y = null, z = 3
x = 3, y = null, z = 1
x = 3, y = 1, z = null
x = null, y = 1, z = 3
x = null, y = 3, z = 1