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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 add(self, message):
 """ Add a new validation message to this instance. Args: message (ValidationMessage):
 A validation message to add to this instance's list of messages. """

        if not isinstance(message, ValidationMessage):
            raise TypeError("Argument must of type ValidationMessage")
        self.messages.append(message)