input: Write a function to print the first five prime numbers.
  assert first_five_primes() == [2, 3, 5, 7, 11]
output: def first_five_primes():
      primes = []
      num = 2
      while len(primes) < 5:
          is_prime = True
          for i in range(2, int(num ** 0.5) + 1):
              if num % i == 0:
                  is_prime = False
                  break
          if is_prime:
              primes.append(num)
          num += 1
      return primes