10 is \lock $foo, \$foo, 'lock returns a scalar argument';
11 is lock @foo, \@foo, 'lock returns a ref to its array argument';
12 is lock %foo, \%foo, 'lock returns a ref to its hash argument';
13 is lock &foo, \&foo, 'lock returns a ref to its code argument';
15 sub eulavl : lvalue { $x }
16 is lock &eulavl, \&eulavl, 'lock returns a ref to its lvalue sub arg';