[Python-ideas] Support reversed(itertools.chain(x, y, z))

Today I had a need: I had a tuple of dynamic sequence-like objects. I wanted to iterate on them reversed, starting with items of the last one and slowly making my way towards the first one. In short, I want `reversed(itertools.chain(x, y, z))` that behaves like `itertools.chain(map(reversed, (z, y, x)))`. What do you think?