Description:
TestMaster.ts define Master、Child、Interface
Index.ts define "CallSave" function to invok "Save" method of "Master".

Loading Credentials in Node.js from Environment Variables
https://docs.aws.amazon.com/zh_cn/sdk-for-javascript/v2/developer-guide/loading-node-credentials-environment.html

Also I have created a table called "TS_LIST" in DYNAMODB.

Steps:
1.	Please use “npm install” to download the package, such as "aws-sdk"、"uuid"、"node types".
2.	Compile testmaster.ts, use "tsc testmaster.ts", it threw these errors, but we didn’t find the way to solve them.
3.	Compile index.ts file, use:  "tsc index.ts".
4.	Run the index.js, use: "node index.js".