input: Write a python function to split an IP address into its four octets.
  assert split_ip("123.235.123.245") == ["123", "235", "123", "245"]
  assert split_ip("54.72.56.14") == ["54", "72", "56", "14"]
  assert split_ip("182.193.146.172") == ["182", "193", "146", "172"]
output: def split_ip(ip):
      return ip.split('.')