[yt-dev] Issue #840: yt.analysis_modules.level_sets.api.find_clumps raises NotImplementedError (yt_analysis/yt)

[Stuart Mumford]

New issue 840: yt.analysis_modules.level_sets.api.find_clumps raises NotImplementedError
https://bitbucket.org/yt_analysis/yt/issue/840/ytanalysis_moduleslevel_setsapifind_clumps

Stuart Mumford:

running `find_clumps.py` from the cook book raises the following error:

```
#!python
Finding clumps: min: 1.000000e-28, max: 1.000000e-23, step: 2.000000
Traceback (most recent call last):
  File "/home/stuart/BitBucket/yt/doc/source/cookbook/find_clumps.py", line 40, in <module>
    find_clumps(master_clump, c_min, c_max, step)
  File "/home/stuart/BitBucket/yt/yt/analysis_modules/level_sets/clump_handling.py", line 171, in find_clumps
    clump.find_children(min_val)
  File "/home/stuart/BitBucket/yt/yt/analysis_modules/level_sets/clump_handling.py", line 110, in find_children
    nj, cids = identify_contours(self.data, self.field, min_val, max_val)
  File "/home/stuart/BitBucket/yt/yt/analysis_modules/level_sets/contour_finder.py", line 36, in identify_contours
    for (g, node, (sl, dims, gi)) in data_source.tiles.slice_traverse():
  File "/home/stuart/BitBucket/yt/yt/utilities/amr_kdtree/amr_kdtree.py", line 189, in slice_traverse
    raise NotImplementedError
NotImplementedError
```