Porting/todo.pod: Rmv ‘LVALUE functions for lists’

Porting/todo.pod: Rmv ‘LVALUE functions for lists’

$ ./perl -Ilib -e 'sub foo :lvalue{@hash{"foo","bar"}} (foo) = (3,4); use Data::Dumper; warn Dumper \%hash'
$VAR1 = {
          'foo' => 3,
          'bar' => 4
        };
$ ./perl -Ilib -e 'sub foo :lvalue{@arr[1,2]} (foo) = (3,4); use Data::Dumper; warn Dumper \@arr'
$VAR1 = [
          undef,
          3,
          4
        ];

Apparently slices do work.