x = t
x, = t
x, y = t
x, y, = t
x, y, z = t
x, y, z, = t
x, y, z, z = a, b, c, d

(x) = t
(x,) = t
(x, y) = t
(x, y,) = t
(x, y, z) = t
(x, y, z,) = t
(x, y, z, z) = a, b, c, d