human
Complete this python program:
def main(reactor, url):
assistant
#Here is the Python program you requested.

    """We create a custom UserAgent and send a GET request to a web server.
    """
    userAgent = ('Twisted/%s    (httpclient.py)' % (version.short(),))
    agent = Agent(reactor)
    d = agent.request('GET', url, Headers({'user-agent': [userAgent]}))
    def cbResponse(response):
        '\n                                Prints    out    the    response    returned    by    the    web    server.\n                                '
        pprint(vars(response))
        proto = WriteToStdout()
        if (response.length is not UNKNOWN_LENGTH):
            print('The    response    body    will    consist    of', response.length, 'bytes.')
        else:
            print('The    response    body    length    is    unknown.')
        response.deliverBody(proto)
        return proto.onConnLost
    d.addCallback(cbResponse)
    d.addErrback(log.err)
    d.addBoth((lambda ign: reactor.callWhenRunning(reactor.stop)))
    reactor.run()