$ ./perl -Ilib -I.. -d:TobyLite -e 'sub x { print qq(ok\n); } sub z { x() } z()' 
>> entering UNIVERSAL::import
<< leaving UNIVERSAL::import 1.40666961669922e-05
>> entering main::z
>> entering main::x
ok
<< leaving main::x 3.29017639160156e-05
<< leaving main::z 8.48770141601562e-05