import itertools
source1_file=["a","b","c","d","e"]
mylist = list(itertools.combinations(source1_file,3))
for i in mylist:
print list(i)
import itertools
source1_file=["a","b","c","d","e"]
mylist = list(itertools.combinations(source1_file,3))
for i in mylist:
print list(i)