Python/ Python Challenge 3

list1 = []
list2 = []

fin = open('foobar.txt')
for line in fin:
    for a in line:
        if a.isupper():
            list1.append("0")
            list2.append(a)
        elif a.islower():
            list1.append("1")
            list2.append(a)

converted = ''.join(list1)
unconverted = ''.join(list2)

win = converted.find('100010001')
print unconverted[win+1:win+8]

def find_all(a_str, sub):
    start = 0
    while True:
        start = a_str.find(sub, start)
        if start == -1: return
        yield start
        start += len(sub)

win1 = list(find_all(converted, '100010001')) # [0, 5, 10, 15]
for a in win1: print unconverted[a:a+9]