How to use the camunda-external-task-client-js.Variables function in camunda-external-task-client-js

const handler = async ({ task, taskService }) => {
  // get task variable 'defaultScore'
  const defaultScore = task.variables.get("defaultScore");

  // set process variable 'creditScores'
  const creditScores = [defaultScore, 9, 1, 4, 10];
  const processVariables = new Variables()
    .set("creditScores", creditScores)
    .set("bar", new Date());

  // complete the task
  try {
    await taskService.complete(task, processVariables);
    console.log("I completed my task successfully!!");
  } catch (e) {
    console.error(`Failed completing my task, ${e}`);
  }
};

client.subscribe("invoiceCreator", async function({ task, taskService }) {
  // Put your business logic
  // complete the task
  const date = new Date();
  const invoice = await new File({ localPath: "./assets/invoice.txt" }).load();
  const minute = date.getMinutes();
  const variables = new Variables().setAll({ invoice, date });

  // check if minute is even
  if (minute % 2 === 0) {
    // for even minutes, store variables in the process scope
    await taskService.complete(task, variables);
  } else {
    // for odd minutes, store variables in the task local scope
    await taskService.complete(task, null, variables);
  }
});

client.subscribe("customer-credit", async function({ task, taskService }) {
  var remainingAmount = 0;
  if (Math.random() > 0.3) {
    remainingAmount = 15;   
  }

  const processVariables = new Variables();
  processVariables.set("remainingAmount", remainingAmount);

  console.log('[%s] done for process instance %s with remainingAmount=%s', task.topicName, task.processInstanceId, remainingAmount);
  await taskService.complete(task, processVariables);
});

client.subscribe("customer-credit", async function({ task, taskService }) {
  var remainingAmount = 0;
  if (Math.random() > 0.3) {
    remainingAmount = 15;   
  }

  const processVariables = new Variables();
  processVariables.set("remainingAmount", remainingAmount);

  console.log('[%s] done for process instance %s with remainingAmount=%s', task.topicName, task.processInstanceId, remainingAmount);
  await taskService.complete(task, processVariables);
});