input: Write a python function to check for IP in an ARP cache and update its status if necessary.
  assert isinstance(check_for_ip(), InetEther)
  assert check_for_ip().is_active == True
  assert check_for_ip().ip == "192.168.1.1"
output: def check_for_ip():
      class InetEther:
          def __init__(self, ip, is_active):
              self.ip = ip
              self.is_active = is_active
  
      # Simulated ARP cache
      arp_cache = {
          "192.168.1.1": InetEther("192.168.1.1", False),
          "192.168.1.2": InetEther("192.168.1.2", True),
          "192.168.1.3": InetEther("192.168.1.3", True),
      }
  
      target_ip = "192.168.1.1"
      if target_ip in arp_cache:
          arp_cache[target_ip].is_active = True
          return arp_cache[target_ip]
      else:
          return InetEther(target_ip, True)