human
Here's a good function header given the following:
I wrote the below code

    (dsp, rd) = os.popen2((sox_base % '-c    2'))
    global x1, x2
    x1 = ''
    x2 = ''
    def play(pkt):
        global x1, x2
        if (not pkt):
            return
        if ((not pkt.haslayer(UDP)) or (not pkt.haslayer(IP))):
            return
        ip = pkt.getlayer(IP)
        if (s1 in [ip.src, ip.dst]):
            if (ip.dst == s1):
                x1 += pkt.getlayer(conf.raw_layer).load[12:]
            else:
                x2 += pkt.getlayer(conf.raw_layer).load[12:]
            (x1, x2, r) = _merge_sound_bytes(x1, x2)
            dsp.write(r)
    sniff(store=0, prn=play, **kargs)

What's a good function header?
assistant
#Here's a good function header.

def voip_play2(s1, **kargs):