Let me trace :
, , so becomes
, , so becomes
, , so becomes
, , so becomes
Loop exits, return true
Now try : , becomes . Then , so return false immediately.
##### ###### ##### ### # # ### # # ###### ## ## ## ## ## ## ## # # # # # ## ##### #### ##### # # # # # # # #### ## # ## ## ## ## # # # # # ## ## # ###### ## ### # ### # ######
##### ###### ##### ### # # ### # # ###### ## ## ## ## ## ## ## # # # # # ## ##### #### ##### # # # # # # # #### ## # ## ## ## ## # # # # # ## ## # ###### ## ### # ### # ######
Tracing an example
Let me trace :
, , so becomes
, , so becomes
, , so becomes
, , so becomes
Loop exits, return true
Now try : , becomes . Then , so return false immediately.