'Watch an address. Everytime the address changes, a http POST is sent to the URL.'

@command('n')
def notify(self, address, URL):

    def callback(x):
        import urllib2
        headers = {'content-type': 'application/json'}
        data = {'address': address, 'status': x.get('result')}
        try:
            req = urllib2.Request(URL, json.dumps(data), headers)
            response_stream = urllib2.urlopen(req, timeout=5)
            util.print_error(('Got    Response    for    %s' % address))
        except BaseException as e:
            util.print_error(str(e))
    self.network.send([('blockchain.address.subscribe', [address])], callback)
    return True
