AWS Invoke One Lambda Function From Another

In AWS Lambda, how to invoke one Lambda function from another ?

Here is a sample JavaScript lambda function invoking another Lambda function (setMFA),

const aws = require('aws-sdk')
exports.handler =  async function(event, context) {
  const lambda = new aws.Lambda({
    region: 'us-west-2'
  });
  let mfaResponse = await lambda.invoke({
    FunctionName: 'setMFA',
    Payload: JSON.stringify(
      userPoolId : "userPoolId",
      username : "Username",
      mfa : true
    )
  }
}

For this to work the invoking lambda function will require permissions to lambda:InvokeFunction.