
* the following should not have a connection from N_RETURN:
  if ( $a == 5 ) { return 1; } print $a; 

* handle "$c = 5 if $a == 8;" and "$c = 5 unless $a == 8;"
  ( no "()" around the condition)

* handle do { ... } until/while ();

* $a++ until $a > 9;

* $a++ while $a < 9;

