input: 
  def is_prime_number(num: int) -> None:
      """
      Determines if a given number is prime or not.
      >>> is_prime_number(17)
      17 is a prime number.
      >>> is_prime_number(15)
      15 is not a prime number.
      """
      is_prime = True
      for i in range(2, num):
          if num % i == 0:
              is_prime = False
              break
      if is_prime:
          print(f'{num} is a prime number.')
      else:
          print(f'{num} is not a prime number.')
  
output:     is_prime = True
      for i in range(2, num):
          if num % i == 0:
              is_prime = False
              break
      if is_prime:
          print(f'{num} is a prime number.')
      else:
          print(f'{num} is not a prime number.')