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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 encode(self):
 """Encode the DAT packet based on instance variables, populating self.buffer, returning self."""

        fmt = b"!HH%dsx" % len(self.errmsgs[self.errorcode])
        log.debug("encoding ERR packet with fmt %s", fmt)
        self.buffer = struct.pack(fmt,
                                  self.opcode,
                                  self.errorcode,
                                  self.errmsgs[self.errorcode])
        return self