exports.handler = async (event) => {
    var aws = require('aws-sdk');
    
    var sts = new aws.STS({ region: process.env.REGION });
    var stsParams = {
      RoleArn: "arn-of-role-in-other-account",
      DurationSeconds: 3600,
      RoleSessionName: "Any string"
    };
    const stsResults = await sts.assumeRole(stsParams).promise();
    console.log(stsResults);
    

    var lambda = new aws.Lambda({
      region: process.env.REGION, 
      accessKeyId: stsResults.Credentials.AccessKeyId, 
      secretAccessKey:stsResults.Credentials.SecretAccessKey, 
      sessionToken: stsResults.Credentials.SessionToken
    });
    const result = await lambda.invoke({
      FunctionName: 'arn-of-function-in-other-account',
      InvocationType: 'RequestResponse',
      Payload: "{}" // pass params
    }).promise();
    
    console.log("The result was: " + JSON.stringify(result));
    
    const response = {
        statusCode: 200,
        body: result.Payload
    };
    return response;
};