requestion regarding regular expression

[BartlebyScrivener]

Kent,

Running

path = "d:/emacs files/emacsinit.txt"
lines = open(path).readlines()
# my defun lines are lowercase,
# next two lines are all on one
starts = [i for i, line in enumerate(lines) if
line.startswith('(defun')]
for i, start in starts:
    while start > 0 and lines[start-1].startswith(';'):
        starts[i] = start = start-1
        print starts

I get

File "D:\Python\findlines.py", line 7, in __main__
    for i, start in starts:
TypeError: unpack non-sequence

Also, I don't understand the "i for i", but I don't understand a lot of
things yet :)

thanks,

rick