if( ! function_exists( "is_child" ) )
    {
        function is_child( $parent = '' )
        {
            global $post, $wp_query;
    
            if ( ! isset( $wp_query ) )
            {
           		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1' );
           		return false;
           	}
    
            if( 0 === $post->post_parent )
                return false;
    
           	if ( is_int( $parent ) && $parent === $post->post_parent )
           		return true;
    
            $parent_obj = get_page( $post->post_parent );
    
            if( ! is_object( $parent_obj ) || is_wp_error( $parent_obj ) )
                return false;
    
            return $parent === $parent_obj->post_title or $parent === $parent_obj->post_name;
        }
    }