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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 sign_all_unsigned_inputs(hex_privkey, unsigned_tx_hex):
 """ Sign a serialized transaction's unsigned inputs @hex_privkey: private key that should sign inputs @unsigned_tx_hex: hex transaction with unsigned inputs Returns: signed hex transaction """

    inputs, outputs, locktime, version = deserialize_transaction(unsigned_tx_hex)
    tx_hex = unsigned_tx_hex
    for index in xrange(0, len(inputs)):
        if len(inputs[index]['script_sig']) == 0:

            # tx with index i signed with privkey
            tx_hex = sign_transaction(str(unsigned_tx_hex), index, hex_privkey)
            unsigned_tx_hex = tx_hex

    return tx_hex