How to make the result type not 'any', but match the argument type using Generics?

In order for the foo function to accept an argument of type any and return a value of the same type, you need to use Generic types in TypeScript. This allows preserving the argument's type and using it as the result type.

Example:

function foo<T>(arg: T): T {
  return arg;
}

// Usage:
const num = foo(123);      // type of num: number
const str = foo('hello');  // type of str: string
const obj = foo({a: 1});   // type of obj: { a: number }

Here, T is a type parameter that is inferred from the passed argument, and the function returns a value of the same type.