gistfile1.txt

import pymongo
import time

servers = ['mongo1', 'mongo2']
master = pymongo.Connection(servers)
print "MASTER is: %s" % master.host

slave = pymongo.Connection(
    [x for x in servers if x != master.host][0], slave_okay=True)

master.monitor.lag.save({'_id':'marker', 'now': time.time()})

print slave.admin.command(
    pymongo.son.SON([('serverStatus', 1), ('repl', 2)])
        )['repl']['sources'][0]['lagSeconds']

print master.monitor.lag.find_one()
print slave.monitor.lag.find_one()