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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_message(self):
 """Encode message to AMQP wire-encoded bytearray. :rtype: bytearray """

        if not self._message:
            raise ValueError("No message data to encode.")
        cloned_data = self._message.clone()
        self._populate_message_attributes(cloned_data)
        encoded_data = []
        c_uamqp.get_encoded_message_size(cloned_data, encoded_data)
        return b"".join(encoded_data)