Documentation for Plural G-algebra support?

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Googling seems to show that Sage supports calculations in certain non-commutative rings (see e.g. http://trac.sagemath.org/sage_trac/ti...).

However I'm having trouble finding enough documentation to get started with this. Can anyone point me to some, or failing this say how to build a g-algebra, add and multiply elements, and test elements for equality? Thank you!