blockSize = 100
fileList = ["filepath1", "filepath2", "filepath3"]

def invert(x):
    return ~x & 0xFF

def repair(filePath, blockSize):
    try:
        with open(filePath,"rb+") as f:
            block = f.read(blockSize)
            newStr = ''
            for ch in block:
                uc = ord(ch)
                inv = invert(uc) 
                newStr += chr(inv)
            f.seek(0)
            f.write(newStr)
            f.close()
            
    except Exception, e:
        raise e
    
    print "Successful!"

for f in fileList:
    try:
        repair(f, blockSize)
    except Exception, e:
        print e