<rpc>
    <get-xxx>
    </get-xxx>
</rpc>

from ncclient import manager


def connect(host, port, user, password):
conn = manager.connect(host=host,
        port=port,
        username=user,
        password=password,
        timeout=10,
        device_params = {'name':'junos'},
        hostkey_verify=False)


result = conn.get_chassis_inventory()
print ("Chassis:", result.xpath('//chassis/description')[0].text)
print ("Chassis Serial-Number:", result.xpath('//chassis/serial-number')[0].text)

result2 = conn.get_system_uptime_information()
print(result2.xpath('//system-booted-time/date-time')[0].text)

if __name__ == '__main__':
connect('192.168.250.254', 830, 'root', 'root123')