public function replace_variables( $str )
	{
		if ( preg_match( "/^\{([A-Z0-9_]+)\}$/", $str, $matches ) ) {
			$key = $matches[1];
			if ( $this->get_variables( $key ) ) {
				return $this->get_variables( $key );
			}
		}
		return $str;
	}