How to create a generic from list of interfaces

I have 2 interfaces and AllTypes type:

interface A {
    // ...
}

interface B {
    // ...
}

type AllTypes = A | B;

How can I use a generic to make sure an argument to a function is object with interface A or B?

// pseudocode
function test<T oneof AllTypes>(argument: T): void {
    // ...
}

>Solution :

Try this:
<T extends AllTypes>