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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _write_packet(self, packet, sec=None, usec=None, caplen=None, wirelen=None):
 """ Writes a single packet to the pcap file. :param packet: Packet, or bytes for a single packet :type packet: Packet or bytes :param sec: time the packet was captured, in seconds since epoch. If not supplied, defaults to now. :type sec: int or long :param usec: If ``nano=True``, then number of nanoseconds after the second that the packet was captured. If ``nano=False``, then the number of microseconds after the second the packet was captured. If ``sec`` is not specified, this value is ignored. :type usec: int or long :param caplen: The length of the packet in the capture file. If not specified, uses ``len(raw(packet))``. :type caplen: int :param wirelen: The length of the packet on the wire. If not specified, tries ``packet.wirelen``, otherwise uses ``caplen``. :type wirelen: int :returns: None :rtype: None """

        if hasattr(packet, "time"):
            if sec is None:
                sec = int(packet.time)
                usec = int(round((packet.time - sec) *
                                 (1000000000 if self.nano else 1000000)))
        if usec is None:
            usec = 0

        rawpkt = raw(packet)
        caplen = len(rawpkt) if caplen is None else caplen

        if wirelen is None:
            if hasattr(packet, "wirelen"):
                wirelen = packet.wirelen
        if wirelen is None:
            wirelen = caplen

        RawPcapWriter._write_packet(
            self, rawpkt, sec=sec, usec=usec, caplen=caplen, wirelen=wirelen)