'Called to implement evaluation of self[key].
>>> ip=IP(\'127.0.0.0/30\')
>>> for x in ip:
...  print str(x)
127.0.0.0
127.0.0.1
127.0.0.2
127.0.0.3
>>> print str(ip[2])
127.0.0.2
>>> print str(ip[-1])
127.0.0.3'

def __getitem__(self, key):

    return IP(IPint.__getitem__(self, key))
