BT Pes 10b(23) :הינו דנפק הינו דעייל‏ : the one [i.e. the mouse] that goes out is the (same) one that goes in (afterwards)
See the entire entry for hyynw pron. this is, that is

BT Pes 10b(23) :הינו דנפק הינו דעייל‏ : the (mouse) that comes out is the (same) one that goes in (afterwards)
See the entire entry for npq vb. to go out