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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 put_if_empty(self, key, value):
 """ Atomically write data only if the key is not already set. :param bytes key: Key to check/set. :param bytes value: Arbitrary data. :return: Boolean whether key/value was set. """

        if self.has_data_for_key(key):
            return False
        self.put_data(key, value)
        return True