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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 tx_verify( cls, verified_block_txids, tx ):
 """ Given the block's verified block txids, verify that a transaction is legit. @tx must be a dict with the following fields: * locktime: int * version: int * vin: list of dicts with: * vout: int, * hash: hex str * sequence: int (optional) * scriptSig: dict with: * hex: hex str * vout: list of dicts with: * value: float * scriptPubKey: dict with: * hex: hex str """

        tx_hash = cls.tx_hash( tx )
        return tx_hash in verified_block_txids