protected function property( $slug = '' ) {
		if ( isset( $this->properties[$slug] ) && papi_is_property( $this->properties[$slug] ) ) {
			$property = $this->properties[$slug];
		} else {
			$property = $this->properties[$slug] = $this->get_property( $slug );
		}

		/**
		 * Modify property.
		 *
		 * @param  Papi_Core_Property $property
		 */
		return apply_filters( 'papi/get_property', $property );
	}