Canvas.cgm() doesn't seem to work

[ghost]

@doutriaux1 looks like this one is either deprecated or not implemented. Let me know which and I will note it in the docs.

>>> a=vcs.init()
>>> array=[range(10) for _ in range(10)]
>>> a.plot(array)
>>> a.cgm('bars.cgm')
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-57-289541cfb4d2> in <module>()
----> 1 a.cgm('bars')

/Users/brown308/anaconda/envs/2.8/lib/python2.7/site-packages/vcs/Canvas.pyc in cgm(self, file, mode)
   4010                 "cgm only supports 'w' mode ignoring your mode ('%s')" %
   4011                 mode)
-> 4012         return self.backend.cgm(file)
   4013 
   4014     def clear(self, *args, **kargs):

/Users/brown308/anaconda/envs/2.8/lib/python2.7/site-packages/vcs/VTKPlots.pyc in cgm(self, file)
   1238             plot.hideWidgets()
   1239 
-> 1240         writer = vtk.vtkIOCGM.vtkCGMWriter()
   1241         writer.SetFileName(file)
   1242         R = self.renWin.GetRenderers()

AttributeError: 'module' object has no attribute 'vtkIOCGM'