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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 start_entry(self, target, var_id):
 """Begin a new config database entry. If there is a current entry in progress, it is aborted but the data was already committed to persistent storage so that space is wasted. Args: target (SlotIdentifer):
 The target slot for this config variable. var_id (int):
 The config variable ID Returns: int: An error code from the global Errors enum. """


        self.in_progress = ConfigEntry(target, var_id, b'')

        if self.data_size - self.data_index < self.in_progress.data_space():
            return Error.DESTINATION_BUFFER_TOO_SMALL

        self.in_progress.data += struct.pack("<H", var_id)
        self.data_index += self.in_progress.data_space()

        return Error.NO_ERROR