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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 check_tx(self, raw_transaction):
 """Validate the transaction before entry into the mempool. Args: raw_tx: a raw string (in bytes) transaction. """


        self.abort_if_abci_chain_is_not_synced()

        logger.debug('check_tx: %s', raw_transaction)
        transaction = decode_transaction(raw_transaction)
        if self.bigchaindb.is_valid_transaction(transaction):
            logger.debug('check_tx: VALID')
            return ResponseCheckTx(code=CodeTypeOk)
        else:
            logger.debug('check_tx: INVALID')
            return ResponseCheckTx(code=CodeTypeError)