input: Write a function to find and print all prime numbers up to a given number n using Python. The function should return None.
  def find_primes_up_to(n):
      def is_prime(num):
          for i in range(2, int(num ** 0.5) + 1):
              if num % i == 0:
                  return False
          return True
      
      for number in range(2, n + 1):
          if is_prime(number):
              print(number)
      return None
  
  assert find_primes_up_to(5) == None
  assert find_primes_up_to(10) == None
  assert find_primes_up_to(20) == None
  assert find_primes_up_to(0) == None
  assert find_primes_up_to(-5) == None
output: def find_primes_up_to(n):
      def is_prime(num):
          for i in range(2, int(num ** 0.5) + 1):
              if num % i == 0:
                  return False
          return True
      
      for number in range(2, n + 1):
          if is_prime(number):
              print(number)
      return None