How to use the pywaves.crypto.sha256 function in PyWaves

for i in range(5):
                r = crypto.bytes2str(os.urandom(4))
                x = (ord(r[3])) + (ord(r[2]) << 8) + (ord(r[1]) << 16) + (ord(r[0]) << 24)
                w1 = x % wordCount
                w2 = ((int(x / wordCount) >> 0) + w1) % wordCount
                w3 = ((int((int(x / wordCount) >> 0) / wordCount) >> 0) + w2) % wordCount
                words.append(wordList[w1])
                words.append(wordList[w2])
                words.append(wordList[w3])
            self.seed = ' '.join(words)
        if publicKey:
            pubKey = base58.b58decode(publicKey)
            privKey = ""
        else:
            seedHash = crypto.hashChain(struct.pack(">L", nonce) + crypto.str2bytes(self.seed))
            accountSeedHash = crypto.sha256(seedHash)
            if not privateKey:
                privKey = curve.generatePrivateKey(accountSeedHash)
            else:
                privKey = base58.b58decode(privateKey)
            pubKey = curve.generatePublicKey(privKey)
        unhashedAddress = chr(1) + str(pywaves.CHAIN_ID) + crypto.hashChain(pubKey)[0:20]
        addressHash = crypto.hashChain(crypto.str2bytes(unhashedAddress))[0:4]
        self.address = base58.b58encode(crypto.str2bytes(unhashedAddress + addressHash))
        self.publicKey = base58.b58encode(pubKey)
        if privKey != "":
            self.privateKey = base58.b58encode(privKey)