groupIndex = 0
for group in self.groups:
# ....
groupIndex += 1
for groupIndex in xrange(len(self.groups)):
#.....
groupIndex = 0
for group in self.groups:
# ....
groupIndex += 1
for groupIndex in xrange(len(self.groups)):
#.....
>>> for num, elem in enumerate('abcd'):
print num, elem
0 a
1 b
2 c
3 d