def pkt2uptime(pkt, HZ=100):
    """Calculate the date the machine which emitted the packet booted using TCP timestamp  # noqa: E501
pkt2uptime(pkt, [HZ=100])"""
    if not isinstance(pkt, Packet):
        raise TypeError("Not a TCP packet")
    if isinstance(pkt, NoPayload):
        raise TypeError("Not a TCP packet")
    if not isinstance(pkt, TCP):
        return pkt2uptime(pkt.payload)
    for opt in pkt.options:
        if opt[0] == "Timestamp":
            # t = pkt.time - opt[1][0] * 1.0/HZ
            # return time.ctime(t)
            t = opt[1][0] / HZ
            return t
    raise TypeError("No timestamp option")