Concatenation is the most fundamental operation that can be done on iterators. In fact, we already do that with lists. [1, 2, 3] + [4, 5, 6] # evaluates to [1, 2, 3, 4, 5, 6] I propose: iter([1, 2, 3]) + iter([4, 5, 6]) # evaluates to something like itertools.chain(iter([1, 2, 3]), iter([4, 5, 6])) # equivalent to iter([1, 2, 3, 4, 5, 6]) There is some python2 code where: a = dict(zip('abcd', range(4))) isinstance(a.values(), list) alphabet = a.keys() + a.values() In python2, this `alphabet` becomes a list of all values and keys In current python3, this raises: TypeError: unsupported operand type(s) for +: 'dict_keys' and 'dict_values' But in my proposal, it works just fine. `alphabet` becomes an iterator over all values and keys (similar to the python2 case). Sincerely, Sam G