Unsets the NV/IV status of an SV.
=for apidoc Am|bool|SvOK|SV* sv
-Returns a boolean indicating whether the value is an SV.
+Returns a boolean indicating whether the value is an SV. It also tells
+whether the value is defined or not.
=for apidoc Am|bool|SvIOKp|SV* sv
Returns a boolean indicating whether the SV contains an integer. Checks
#define SvPVbyte_force(sv, lp) \
((SvFLAGS(sv) & (SVf_POK|SVf_UTF8|SVf_THINKFIRST)) == (SVf_POK) \
- ? ((lp = SvCUR(sv)), SvPVX(sv)) : sv_pvbyte_force(sv, &lp))
+ ? ((lp = SvCUR(sv)), SvPVX(sv)) : sv_pvbyten_force(sv, &lp))
#define SvPVbyte_nolen(sv) \
((SvFLAGS(sv) & (SVf_POK|SVf_UTF8)) == (SVf_POK)\