input: Write a python function to count the number of cats and dogs in a list.
  assert count_animals(["cat", "dog", "cat", "dog", "cat"]) == (3, 2)
  assert count_animals(["dog", "dog", "dog", "cat"]) == (1, 3)
  assert count_animals(["cat", "cat", "cat", "cat"]) == (4, 0)
output: def count_animals(animals):
      cats = animals.count("cat")
      dogs = animals.count("dog")
      return cats, dogs