This is an alternative to itertools.tee. It has the same interface but

This implementation never holds on to generated values "unnecesarily", in particular, if you do

iter2 = streamtee.tee(iter1, 2)[0]

then iter2 stops referring to an object when iter1 would have done so. The fact that you `leak' a tee-ed stream here does not matter for memory use.

The test.py file generates two files streamtee.out and itertools.out. By comparing these you will notice that the output is identical except that streamtee.out shows that objects are being deleted earlier.

The implementation is based on the functional language concept of "lazy streams". We convert from a Python iterator to a lazy stream. Then the lazy stream is converted back to the desired number of Python iterators.