human
I wrote the below code

    (dsp, rd) = os.popen2((sox_base % ''))
    def play(pkt):
        if (not pkt):
            return
        if ((not pkt.haslayer(UDP)) or (not pkt.haslayer(IP))):
            return
        ip = pkt.getlayer(IP)
        if (s1 == ip.src):
            dsp.write(pkt.getlayer(conf.raw_layer).load[12:])
    try:
        if (lst is None):
            sniff(store=0, prn=play, **kargs)
        else:
            for p in lst:
                play(p)
    finally:
        dsp.close()
        rd.close()

What's a good function header?

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

def voip_play(s1, lst=None, **kargs):