digraphs.nauty_directg() missing in SageMath 8.6?

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Hello, I recently picked up SageMath to perform digraph computations regarding a research interest. I'm running into a strange issue regarding a function that should exist, judging by the documentation (link at the bottom of this post), but apparently does not. If I attempt to run a small test copied directly from said documentation:

gen = graphs.nauty_geng("-c 3")
dgs = list(digraphs.nauty_directg(gen))

the program fails to compile and yields

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-29-ae6a73f0fd49> in <module>()
      1 gen = graphs.nauty_geng("-c 3")
----> 2 dgs = list(digraphs.nauty_directg(gen))

/opt/sagemath-8.6/local/lib/python2.7/site-packages/sage/misc/lazy_import.pyx in sage.misc.lazy_import.LazyImport.__getattr__ (build/cythonized/sage/misc/lazy_import.c:3536)()
    320             True
    321         """
--> 322         return getattr(self.get_object(), attr)
    323 
    324     # We need to wrap all the slot methods, as they are not forwarded

AttributeError: DiGraphGenerators instance has no attribute 'nauty_directg'

Could anyone tell me whether I'm I making a horrible rookie mistake, or is this functionality is simply missing from SageMath 8.6? Or is there something else at play?

Thanks, Pepijn

Documentation at: http://doc.sagemath.org/html/en/reference/graphs/sage/graphs/digraph_generators.html#sage.graphs.digraph_generators.DiGraphGenerators.nauty_directg