RuntimeError in collab example

[Game4Move78]

Simply run the Collab notebook:

https://colab.research.google.com/gist/bwasti/4ba286e0a6ce9d39ec50c0e1ebf7d428/loop_tool_lowlevel_sweep.ipynb

---------------------------------------------------------------------------

RuntimeError                              Traceback (most recent call last)

[<ipython-input-11-6393985f1619>](https://localhost:8080/#) in <module>()
     83         vec = 2 ** vec_pow
     84         inner = inner // vec
---> 85         b, c, l = test_pw(s, inner, vec)
     86         if b > best:
     87             best = b

[<ipython-input-11-6393985f1619>](https://localhost:8080/#) in test_pw(size, inner_size, vec_size)
     42     C.set(1337.0)
     43     parallel = set(loop_tree.children(loop_tree.roots[0]))
---> 44     c = lt.cuda(loop_tree, parallel)
     45     c([A, B, C])
     46     C_test = C.to_numpy()

RuntimeError: assertion: trivially_parallel(lt, ref) && "Loop not yet threadable! TODO: warp-level reductions" failed @ /tmp/pip-req-build-kiwb6ql5/src/backends/cuda/cuda.cpp:988