+--- aliasing ---
+
+$x # 1 for $x->{a}; () # '', undef, { a => undef }
+$x # 1 for $x->{a}; () # '', undef, undef #
+$x # 1 for $x->{a}; () # '', undef, undef # +fetch
+$x # 1 for $x->{a}; () # '', undef, { a => undef } # +exists
+$x # 1 for $x->{a}; () # '', undef, { a => undef } # +delete
+$x # 1 for $x->{a}; () # '', undef, { a => undef } # +store
+
+$x # $_ = 1 for $x->{a}; () # '', undef, { a => 1 }
+$x # $_ = 1 for $x->{a}; () # '', undef, undef #
+$x # $_ = 1 for $x->{a}; () # '', undef, undef # +fetch
+$x # $_ = 1 for $x->{a}; () # '', undef, { a => 1 } # +exists
+$x # $_ = 1 for $x->{a}; () # '', undef, { a => 1 } # +delete
+$x # $_ = 1 for $x->{a}; () # '', undef, { a => 1 } # +store
+
+$x->{a} = 1 # 1 for $x->{a}; () # '', undef, { a => 1 } # +fetch
+$x->{a} = 1 # 1 for $x->{b}; () # '', undef, { a => 1, b => undef } # +fetch
+$x->{a} = 1 # 1 for $x->{a}; () # '', undef, { a => 1 } # +exists
+$x->{a} = 1 # 1 for $x->{b}; () # '', undef, { a => 1, b => undef } # +exists
+$x->{a} = 1 # 1 for $x->{a}; () # '', undef, { a => 1 } # +delete
+$x->{a} = 1 # 1 for $x->{b}; () # '', undef, { a => 1, b => undef } # +delete
+$x->{a} = 1 # 1 for $x->{a}; () # '', undef, { a => 1 } # +store
+$x->{a} = 1 # 1 for $x->{b}; () # '', undef, { a => 1, b => undef } # +store
+