input: Write a function to check if a number is within the range of 1 to 10 (inclusive). If it is within the range, return True. Otherwise, return False. If the input is None, return None.
  assert check_number(5) == True
  assert check_number(10) == True
  assert check_number(1) == True
  assert check_number(11) == False
  assert check_number(0) == False
  assert check_number(None) == None
output: def check_number(num):
      if num is None:
          return None
      return 1 <= num <= 10