as referecne:
<a href='https://medium.com/nchain/simplified-payment-verification-48ac60f1b26c'>https://medium.com/nchain/simplified-payment-verification-48ac60f1b26c</a>
as referecne:
<a href='https://medium.com/nchain/simplified-payment-verification-48ac60f1b26c'>https://medium.com/nchain/simplified-payment-verification-48ac60f1b26c</a>