将查询与修饰符分离

refactorgram

function getTotalOutstandingAndSendBill() {
  const result = customer.invoices.reduce((total, each) => each.amount + total, 0);
  sendBill();
  return result;
}

function totalOutstanding() {
  return customer.invoices.reduce((total, each) => each.amount + total, 0);  
}
function sendBill() {
  emailGateway.send(formatBill(customer));
}