code: def to_ipv4(self):
          
          if self.v == 4:
              return self
          else:
              if self.bin().startswith('0' * 96):
                  return IP(int(self), version=4)
              elif self.bin().startswith('0' * 80 + '1' * 16):
                  return IP(int(self) & MAX_IPV4, version=4)
              elif int(self) & BASE_6TO4:
                  return IP((int(self) - BASE_6TO4) >> 80, version=4)
              else:
                  return ValueError('%s: IPv6 address is not IPv4 compatible or mapped, '
                                    'nor an 6-to-4 IP' % self.dq)
docs: Convert (an IPv6) IP address to an IPv4 address, if possible.
  
          Only works for IPv4-compat (::/96), IPv4-mapped (::ffff/96), and 6-to-4
          (2002::/16) addresses.
  
          >>> ip = IP('2002:c000:022a::')
          >>> print(ip.to_ipv4())
          192.0.2.42