Type Predicates 2

function isCat(pet: Pet): pet is Cat {
  return "microchip" in pet
}

function isDog(pet: Pet): pet is Dog {
  return "collar" in pet
}

function getName(pet: Pet): string {
  if (isDog(pet)) return pet.collar.name
  if (isCat(pet)) return pet.microchip.name
}