>perl -wle"print( prototype( 'CORE::chomp' ) )"
Use of uninitialized value in print at -e line 1.   <- Can't


>perl -wle"print( prototype( 'CORE::push' ) )"
\@@                                                 <- Can

##</code><code>##

BEGIN {
   *CORE::GLOBAL::push = sub(\@@) {
      my $array = shift(@_);
      print("Pushing\n");
      return CORE::push(@$array, @_);
   };
}