x.x = 1
x.y = 2
x.z = 3
x.z = 4
x.x = 1
x.y = 2
x.z = 4
x.y.m = 7
OK: y in with scope is undefined
x.zz = 1
OK: x in with scope is undefined
x.x = undefined
x.y = undefined
x.z = 4
x.zz = 1100
q.a = 2
q.zz = 1100
a is called