comparison-not-easy.ts

export class Mammal {
  mammalName: string;
}
export class Dog extends Mammal {
  dogName: string;
}
export class Cat extends Mammal {
  catName: string;
}

const cat: Cat = { catName: 'kitty' };
const dog: Dog = { dogName: 'doggo' };

export function compare<T>(a: T, b: T): number {
  // ... implementation
}

// Guess what is the inferred type of `T` here
const comparationResult = comparator(cat, dog);