Fix "six.moves import range zip intern input" during PyOpenCL installation

I installed PyOpenCL using pip (pip install pyopencl), when executing a script within tutorial found online, I encountered the following bug

$ python main.py
Traceback (most recent call last):
File "main.py", line 4, in <module>
import pyopencl as cl
File "/usr/local/lib/python2.7/dist-packages/pyopencl/__init__.py", line 762, in <module>
_add_functionality()
File "/usr/local/lib/python2.7/dist-packages/pyopencl/__init__.py", line 379, in _add_functionality
from pytools import memoize_method
File "/usr/local/lib/python2.7/dist-packages/pytools/__init__.py", line 5, in <module>
from six.moves import range, zip, intern, input
ImportError: cannot import name intern
[~/Dropbox/proj/openCLtest] $ python main.py
Traceback (most recent call last):
File "main.py", line 5, in <module>
import pyopencl as cl
File "/usr/local/lib/python2.7/dist-packages/pyopencl/__init__.py", line 762, in <module>
_add_functionality()
File "/usr/local/lib/python2.7/dist-packages/pyopencl/__init__.py", line 379, in _add_functionality
from pytools import memoize_method
File "/usr/local/lib/python2.7/dist-packages/pytools/__init__.py", line 5, in <module>
from six.moves import range, zip, intern, input
ImportError: cannot import name intern

 I fixed it by updating "Six".

pip install --upgrade Six

That's it!

Enjoy.