One could use generators to produce a modified iterable without copying e.g. here's genexpr is used to define generator: squared = (x*x for x in iterable)

One could use generators to produce a modified iterable without copying e.g. here's genexpr is used to define generator: squared = (x*x for x in iterable) In general, a generator function can be used if necessary: def squared(iterable): for x in iterable: yield x*x