Swapped buffer and target array in example 021

[OllePenttinen]

Thank you so much for your contribution related to pyOpenCL. Helps a lot. I tried your example https://github.com/benshope/PyOpenCL-Tutorial/blob/master/021_array_sum.py

but the variables seem to have been swapped on line 39?

cl.enqueue_copy(queue, cl_arrays[x], np_arrays[x])

should probably read:

cl.enqueue_copy(queue, np_arrays[x], cl_arrays[x])

Best regards Olle