Here are two comparable, 3-letter sequences, "ysxxsy" and "ysxysx".
(on my qwertz keyboard "y" is the first key of the bottom row)
This example illustrates the "overflow" after 3 key presses already, indicated by value 17 changing to 1 (or better said the list where 1st element is "17" has 2nd value changing to "1"). After this the hi object does not output anything until a key is released.
Notice also the difference of the 2nd column, corresponding to the second releasing order: for the first key release action the hi object send out two complete "sets" of lists: