public function markStoryViewed($id, $screenshot_count = 0) {
		// Make sure we're logged in and have a valid access token.
		if (!$this->auth_token || !$this->username) {
			return FALSE;
		}

		// Mark story as viewed.
		$timestamp = parent::timestamp();
		$result = parent::post(
			'/update_stories',
			array(
				'friend_stories' => json_encode(array(
					array(
						'id' => $id,
						'screenshot_count' => $screenshot_count,
						'timestamp' => $timestamp,
					),
				)),
				'timestamp' => $timestamp,
				'username' => $this->username,
			),
			array(
				$this->auth_token,
				$timestamp,
			)
		);

		return is_null($result);
	}