sample.py

from stellar_sdk import TransactionBuilder, Server, Network
import requests

STELLAR_TOML = 'https://api.dstoq.com/.well-known/stellar.toml'
PUBLIC_KEY = 'your-public-key'
APPROVAL_SERVER = 'https://api.dstoq.com/core/sign/tx'

server = Server(horizon_url='https://horizon.stellar.org')
builder = TransactionBuilder(server.load_account(PUBLIC_KEY), Network.PUBLIC_NETWORK_PASSPHRASE)
  
tx_xdr = builder.append_manage_buy_offer_op(
    selling_code='XLM',
    selling_issuer=None,
    buying_code='DEMO',
    buying_issuer='GDWHDCUYIA7LDEIL6XOPYBSRYG3JOFPC2ZF5ZHGTINU4T5E7YA6AMNH5',
    amount='1.00',
    price='1.00'
).build().to_xdr()


requests.post(APPROVAL_SERVER, data={'tx': tx_xdr}).json()