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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 simple_spool_transaction(self, from_address, to, op_return, min_confirmations=6):
 """ Utililty function to create the spool transactions. Selects the inputs, encodes the op_return and constructs the transaction. Args: from_address (str):
 Address originating the transaction op_return (str):
 String representation of the spoolverb, as returned by the properties of Spoolverb min_confirmations (int):
 Number of confirmations when chosing the inputs of the transaction. Defaults to 6 Returns: str: unsigned transaction """

        # list of addresses to send
        ntokens = len(to)
        nfees = old_div(self._t.estimate_fee(ntokens, 2), self.fee)
        inputs = self.select_inputs(from_address, nfees, ntokens, min_confirmations=min_confirmations)
        # outputs
        outputs = [{'address': to_address, 'value': self.token} for to_address in to]
        outputs += [{'script': self._t._op_return_hex(op_return), 'value': 0}]
        # build transaction
        unsigned_tx = self._t.build_transaction(inputs, outputs)
        return unsigned_tx