public function get( $id, $slug ) {
		$fn = $this->get_function( 'get' );

		if ( ! is_callable( $fn ) ) {
			return;
		}

		if ( $this->id ) {
			$value = call_user_func_array( $fn, [$this->type, $id, unpapify( $slug ), true] );
		} else {
			$value = call_user_func_array( $fn, [unpapify( $slug ), null] );
		}

		if ( papi_is_empty( $value ) ) {
			return;
		}

		return $value;
	}