SV *
mu64_eqn(self, other, rev = NULL)
    SV *self
    SV *other
    SV *rev = NO_INIT
PREINIT:
    uint64_t selfu64;
    uint64_t otheru64;
CODE:
    selfu64 = SvU64x(self);
    otheru64 = SvU64(aTHX_ other);
    RETVAL = (selfu64  == otheru64
               ? &PL_sv_yes
               : &PL_sv_no );