TYPEMAP

Key			T_KEY
PMT *                   O_OBJECT

OUTPUT

O_OBJECT
   sv_setref_pv( $arg, "Tree::M", (void*)$var );

INPUT

O_OBJECT
   if( sv_isobject($arg) && (SvTYPE(SvRV($arg)) == SVt_PVMG) )
      $var = ($type)SvIV((SV*)SvRV( $arg ));
   else{
      warn( \"${Package}::$func_name() -- $var is not a blessed SV reference\" );
      XSRETURN_UNDEF;
   }