public class TxHandler {

/**

* Creates a public ledger whose current UTXOPool (collection of unspent transaction outputs) is

* {@code utxoPool}. This should make a copy of utxoPool by using the UTXOPool(UTXOPool uPool)

* constructor.

*/

public TxHandler(UTXOPool utxoPool) {

// IMPLEMENT THIS

}

/**

* @return true if:

* (1) all outputs claimed by {@code tx} are in the current UTXO pool,

* (2) the signatures on each input of {@code tx} are valid,

* (3) no UTXO is claimed multiple times by {@code tx},

* (4) all of {@code tx}s output values are non-negative, and

* (5) the sum of {@code tx}s input values is greater than or equal to the sum of its output

* values; and false otherwise.

*/

public boolean isValidTx(Transaction tx) {

// IMPLEMENT THIS

}

/**

* Handles each epoch by receiving an unordered array of proposed transactions, checking each

* transaction for correctness, returning a mutually valid array of accepted transactions, and

* updating the current UTXO pool as appropriate.

*/

public Transaction[] handleTxs(Transaction[] possibleTxs) {

// IMPLEMENT THIS

}

}