Your example works for me.

>>> x = [1, 2, 3]
>>> y = [4, 5, 6]
>>> zipped = zip(x, y)
>>> print(zipped)
<zip object at 0xb6ff706c>
>>> print(list(zipped))
[(1, 4), (2, 5), (3, 6)]

I guess you have overridden the builtin function "zip" by setting the global variable "zip".

>>> zip = (7, 8)
>>> zipped = zip(x, y)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object is not callable