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import { u8aToHex } from 'https://deno.land/x/polkadot@0.2.40/util/mod.ts';
import { keccakAsU8a } from '../keccak/index.ts';
function isInvalidChar (char: string, byte: number): boolean {  return char !== (    byte > 7      ? char.toUpperCase()      : char.toLowerCase()  );}
export function isEthereumChecksum (_address: string): boolean {  const address = _address.replace('0x', '');  const hash = u8aToHex(keccakAsU8a(address.toLowerCase()), -1, false);
  for (let i = 0; i < 40; i++) {    if (isInvalidChar(address[i], parseInt(hash[i], 16))) {      return false;    }  }
  return true;}