Add selcet_gamma.py (authored by Amnon)
Add selcet_gamma.py (authored by Amnon)

Used in the filtering notebook.

mortonjt/American-Gut,biocore/American-Gut,biocore/American-Gut,JWDebelius/American-Gut,EmbrietteH/American-Gut,wasade/American-Gut,EmbrietteH/American-Gut,JWDebelius/American-Gut,wasade/American-Gut