class Downloadable:
    def __init__(self, url):
        self.url = url
class Downloader(Downloadable):
        __store = ''
        __hashed = ''
        __encoded = ''
        def __init__(self, url, hash):
                Downloadable.__init__(self, url)
        def download(self):
                import urllib2
                r = urllib2.urlopen(self.url)
                global __store
                __store = r.read()
        def hash(self):
                m = hashlib.md5()
                m.update(__store)
                global __hashed
                __hashed = m.hexdigest()
                return __hashed
        def encode(self):
                import base64
                global __store
                global __encoded
                __encoded = base64.b64encode(__store)
                return __encoded
        def isValid(self):
                if self.hash != __hashed:
                        return False
                else: return True