input: Write a python function to validate an IPv4 address.
  assert validateIP("192.168.1.1").validate() == True
  assert validateIP("255.255.255.255").validate() == True
  assert validateIP("256.256.256.256").validate() == False
  assert validateIP("192.168.1").validate() == False
  assert validateIP("abc.def.ghi.jkl").validate() == False
output: def validateIP(ip):
      class Validator:
          def __init__(self, ip):
              self.ip = ip
  
          def validate(self):
              parts = self.ip.split('.')
              if len(parts) != 4:
                  return False
              for part in parts:
                  if not part.isdigit():
                      return False
                  num = int(part)
                  if num < 0 or num > 255:
                      return False
              return True
  
      return Validator(ip)