From msg214692 it seems to me that Alex wants "Python-friendly" formulas or examples, rather than mathematical formulas.  Most functions seems to already have them, so I was asking for a patch to get a better idea of which functions he thinks should be improved and how.

As an example, itertools docs have simple "formulas" explaining what the function does and an example in the table at the top, and (possibly approximate) Python equivalents for most of the functions: https://docs.python.org/dev/library/itertools.html
While the Python equivalent are probably not needed here, some simple formulas/examples might be OK, but I would have to see what exactly Alex is proposing.