In python, can I lazily generate copies of an iterator using tee? -

i'm trying create iterator lazily creates (potentially infinitely many) copies of iterator. possible?

i know can create fixed finite number of copies doing

iter_copies = tee(my_iter, n=10) 

but breaks down if don't know n ahead of time or if n infinite.

i try along lines of

def inf_tee(my_iter):     while true:         yield tee(my_iter)[1] 

but documentation states after using tee on iterator original iterator can no longer used, won't work.

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in case you're interested in application: idea create lazy unzip function, potentially use in pytoolz. current implementation can handle finite number of infinite iterators (which better plain zip(*seq)), not infinite number of infinite iterators. here's pull request if you're interested in details.

this barely touched upon in single example near bottom of itertools documentation, itertools.tee supports copying:

import itertools, copy  def infinite_copies(some_iterable):     master, copy1 = itertools.tee(some_iterable)     yield copy1     while true:         yield copy.copy(master) 

the example in documentation uses __copy__ magic method, hook used customize copy.copy behavior.

note require storing every element ever produced original iterator, can expensive. there no way avoid cost.