reference to a = SCALAR(0x102d4c)
reference to h->{FOO} = SCALAR(0x13bdb8)
in show_refs, ref = SCALAR(0x102d4c)
in show_refs, ref = SCALAR(0x13bdd0)
reverse order ...
in show_refs, ref = SCALAR(0x13bdb8)
in show_refs, ref = SCALAR(0x102d4c)