python enumerate

def enumerate(collection):     'Generates an indexed series:  (0,coll[0]), (1,coll[1]) ...'           i = 0      it = iter(collection)      while 1:      yield (i, it.next())      i += 1

ls1=['a','b','c']

for n,arg in enumerate(ls1):
    print(n,":",arg)

0 : a
1 : b
2 : c