Tracking: new features

[OutSquareCapital]

Tracking issues as a to-do list.

Libraries with interesting features

• boltons

• streamable

• returns

• sortedcontainers (done)

• more-itertools (mostly done)

• toolz/cytoolz (mostly done)

• slicedview (done)

• aioitertools

API improvements

• add adapt or into_adapt to PyoIterator or Iter for return Iter(f(self))
• See of we change iter to into_iter (no python builtin name collision). Or see if we have legitimate use case for into_iter.