HA! You've been forked! !/usr/bin/env python import pdb expected_rngs = range(0,10) file_list = [0, 1, 2, 3, 4, 5, 6, 8, 9] for antenna in expected_rngs[:]: print "*********************************************************************" print "CHECKING", antenna for rng in file_list: print "checking", rng if rng == antenna: expected_rngs.remove(antenna) print "removing", antenna break print "*********************************************************************" print "*********************************************************************" print expected_rngs