let pets = [
  {name: 'Yeller', type: 'Dog', age: 12},
  {name: 'Akumano', type: 'Japanese Bobtail Cat', age: 2},
  {name: 'Meaw Peesard', type: 'Siamese Cat', age: 100},
  {name: 'James', type: 'Gecko', age: 2},
]

const young_pets = (pet) => {
  return pet.age <= 10;
}

const age_pets = (pet) => {
  return [pet.name, pet.age + 10];
}

const name_age = (pet) => {
  return `${pet[0]} is ${pet[1]}`;
}

const debug = (msg) => {
  console.log(msg);
  return msg;
}

const tee = (result, data, cb) => {
  const side = (input) => {
    cb(input, result, data);
    return input;
  }

  return side;
}

let owned_pets = [];
const add_owner_tee = tee(owned_pets, 'Zed', (i, r, d) => {
  r.push({pet: i, owner: d});
});

let age_young_animals = pets.filter(young_pets)
  .map(add_owner_tee)
  .map(age_pets)
  .map(name_age);

console.log("-- Pets with Owners:");
owned_pets.forEach(debug);

console.log("-- Young Animals:");
age_young_animals.forEach(debug);