merge two types typescript

1interface IStudent {
2    id: string;
3    age: number;
4}
5
6interface IWorker {
7    companyId: string;
8}
9
10type IStudentAlias = IStudent;
11
12type ICustomType = IStudent | IWorker;
13
14let s: IStudentAlias = {
15    id: 'ID3241',
16    age: 2
17};