input: Write a function to determine if a given number is prime and print all prime numbers up to a specified upper limit using Python. If the given number is prime, return True; otherwise, return False. If the input is not applicable, then return None.
  assert is_prime(7)==True
  assert is_prime(10)==False
  assert is_prime(11)==True
  assert is_prime(0)==None
  assert is_prime(1)==None
output: def is_prime(n):
      if n <= 1:
          return None
      if n == 2:
          return True
      if n % 2 == 0:
          return False
      for i in range(3, int(n**0.5) + 1, 2):
          if n % i == 0:
              return False
      return True