The sentence of getdata(TX_DATA_TYPE, tx_obj.hash()) which is included the answer of chapter 12 practice 6 In the page 270,

[windwindwa]

The sentence of getdata(TX_DATA_TYPE, tx_obj.hash()) which is included the answer of chapter 12 practice 6 In the page 270,
when I change the parameter tx_obj.hash() to a random data ,the result is success too ,
then I note the sentence , but the result always is success .
so, I have two questions for it, the first one, what is the second parameter tx_obj.hash() effect.
and the second, could you tell me ,why it always print success ,when I note the sentence .