private function set_up_version_numbers() {
		if ( $this->it_has( 'js_version' ) ) {
			$this->js_version = $this->options['js_version'];
		}
		if ( $this->it_has( 'css_version' ) ) {
			$this->css_version = $this->options['css_version'];
		}
		if ( $this->it_has( 'jquery_version' ) ) {
			$this->jquery_version = $this->options['jquery_version'];
		}
	}