How to use the elliptic/lib/elliptic/utils.assert.equal function in elliptic

client.getBalance('BTC', { address: holderAddress }, (err, data) => {
      assert.equal(err, null, err);
      assert(data.utxos.length > 0, `address (${holderAddress}) has not sent or received any bitcoins. Please request funds from the faucet (https://coinfaucet.eu/en/btc-testnet/) and try again.`);
      data.utxos.some((u) => {
        if (u.value >= 10000 && u.height > 0 && u.index !== undefined) {
          utxo = u;
          return true;
        }
      });
      assert(utxo !== undefined, `Unable to find an output with value >=10000 for address ${holderAddress}`);
      done();  
    });
  });