if( $value->isa( "Node" ) ) {
   # It's okay to put $value into the parent attribute
}

##</code><code>##

$obj->parent( 0 );
is( $obj->parent, undef );

##</code><code>##

if( ref( $value ) && ref( $value ) ne "SCALAR" && ref( $value ) ne "ARRAY" && ref( $value ) ne "HASH" && $value->isa( "Node" ) ) {