We can also define generic interfaces using the type variable T, as follows:

interface GenericFunc<T> { 
    (arg: T): T; 
} 
function func<T>(arg: T): T { 
    return arg; 
} 
var myFunc: GenericFunc<number> = func; 

Here, we defined a generic interface and the myFunc variable of the GenericFunc type, passing the number data type for the type variable T. Then, this variable is assigned with a function named func.