x = ()
x = a
x = a,
x = a, 2
x = a, 2,
x = a, 2, 3
x = a, 2, 3, 4
x = a, 2, 3, 4, 5

x = ()
x = (a)
x = (a,)
x = (a, 2)
x = (a, 2,)
x = (a, 2, 3)
x = (a, 2, 3, 4)
x = (a, 2, 3, 4, 5)