$ perl -le 'my $u; sub u :lvalue {$u} print ref \u'
SCALAR

##</code><code>##

$ perl -le 'my $u; sub u :lvalue {$u} print ref \&u'
CODE

##</code><code>##

$ perl -le 'my $u; sub u :lvalue {$u} print ref \u; print \u; print \$u'
SCALAR
SCALAR(0x812dd80)
SCALAR(0x812dd80)