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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 line_print(self):
 """ Return the message as a one-line string. :return: the string representing the message """

        inv_types = {v: k for k, v in defines.Types.items()}

        if self._code is None:
            self._code = defines.Codes.EMPTY.number

        msg = "From {source}, To {destination}, {type}-{mid}, {code}-{token}, ["\
            .format(source=self._source, destination=self._destination, type=inv_types[self._type], mid=self._mid,
                    code=defines.Codes.LIST[self._code].name, token=self._token)
        for opt in self._options:
            msg += "{name}: {value}, ".format(name=opt.name, value=opt.value)
        msg += "]"
        if self.payload is not None:
            if isinstance(self.payload, dict):
                tmp = list(self.payload.values())[0][0:20]
            else:
                tmp = self.payload[0:20]
            msg += " {payload}...{length} bytes".format(payload=tmp, length=len(self.payload))
        else:
            msg += " No payload"
        return msg