if (SvROK(sv) && SvTYPE(sv) == SVt_PVCV)
   warn("sv is a code reference (CV) alright.");

##</code><code>##

if (SvROK(sv) && sv_derived_from(sv, "Foo"))
   warn("sv isa Foo");

##</code><code>##

if (gv_fetchmethod(gv_stashpv("Foo", 0), "Foo::bar"))
   warn("succeeded in finding Foo::bar");