Can not call the solidity smart contract function from web3js

i am try to call a method in solidity smart contract through angular app. but i unable to call the method. can someone please help me. this is the error i get in console TypeError: this.contract.methods.hello is not a function at CertificateContractService.<anonymous> (certificate-contract.service.ts:32) at Generator.next (<anonymous>) at fulfilled (tslib.es6.js:70) at ZoneDelegate.invoke (zone-evergreen.js:359) at Object.onInvoke (core.js:39699)…

How to quickly get the balance of any bitcoin address? (with no third-party API)

As some people have mentioned (eg. here), the only to get the balance of an address was to import it into bitcoin core as a watch-only address and rescan the blockchain. Starting with bitcoin core v0.17, we can use the scantxoutset command, however this is quite slow: > time bitcoin-cli scantxoutset “start” “[\”addr(17Pu3CEx34YX8bpGATq45PfL2fGBCPcr2u)\”]” { “success”:…