input: Write a python function to add an animal to an environment and get the list of all animals.
  assert add_and_get_animals(['Tiger', 'Lion'], 'Giraffe') == ['Tiger', 'Lion', 'Giraffe']
  assert add_and_get_animals([], 'Elephant') == ['Elephant']
  assert add_and_get_animals(['Panda'], 'Kangaroo') == ['Panda', 'Kangaroo']
output: def add_and_get_animals(animals, new_animal):
      animals.append(new_animal)
      return animals