'Send a ping request.
Arguments:
jid        -- The JID that will receive the ping.
ifrom      -- Specifiy the sender JID.
block      -- Indicate if execution should block until
a pong response is received. Defaults
to True.
timeout    -- Time in seconds to wait for a response.
Defaults to self.timeout.
callback   -- Optional handler to execute when a pong
is received. Useful in conjunction with
the option block=False.'

def send_ping(self, jid, ifrom=None, block=True, timeout=None, callback=None):

    if (not timeout):
        timeout = self.timeout
    iq = self.xmpp.Iq()
    iq['type'] = 'get'
    iq['to'] = jid
    iq['from'] = ifrom
    iq.enable('ping')
    return iq.send(block=block, timeout=timeout, callback=callback)
