c:\test>perl -wle"sub TODO{ die 'Unimplemented' } 0 or TODO;"
Unimplemented at -e line 1.

##</code><code>##

c:\test>perl -wle"sub _'_'_{ die 'Unimplemented' } 0 or _'_'_;"
Unimplemented at -e line 1.

c:\test>perl -wle"sub ___{ die 'Unimplemented' } 0 or ___;"
Unimplemented at -e line 1.