def METHOD_NAME(self):
    # print "DEBUG: repr(self.slhead):", repr(self.slhead)
    # print "DEBUG: self.slhead[0 : len(self.INFOSIGNATURE)].lower():",
    # print self.slhead[0 : len(self.INFOSIGNATURE)].lower()
    # print "DEBUG: self.INFOSIGNATURE.lower():",
    #         self.INFOSIGNATURE.lower()
    if self.slhead[0: len(self.INFOSIGNATURE)].lower() == \
            self.INFOSIGNATURE.lower():
        return 0
    # print "DEBUG: self.slhead[0 : len(self.SIGNATURE)].lower():",
    # print self.slhead[0 : len(self.SIGNATURE)].lower()
    # print "DEBUG: self.SIGNATURE.lower():", self.SIGNATURE.lower()
    if not self.slhead[0: len(self.SIGNATURE)].lower() == \
            self.SIGNATURE.lower():
        return -1
    seqbytes = bytes(self.slhead[2:8])
    # print "DEBUG: seqbytes:", seqbytes,", int(seqbytes, 16):", \
    #      int(seqbytes, 16)
    seqnum = -1
    try:
        seqnum = int(seqbytes, 16)
    except Exception:
        msg = "SLPacket.get_sequence_number(): bad packet sequence number:"
        print(msg, seqbytes)
        return -1
    return seqnum