File.appendTo

Gets an output stream for appending data to the file. If the file doesn't already exist it is created.

By default files created are generally readable by everyone, but if you pass [gio.types.FileCreateFlags.Private] in flags the file will be made readable only to the current user, to the level that is supported on the target filesystem.

If cancellable is not null, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error [gio.types.IOErrorEnum.Cancelled] will be returned.

Some file systems don't allow all file names, and may return an [gio.types.IOErrorEnum.InvalidFilename] error. If the file is a directory the [gio.types.IOErrorEnum.IsDirectory] error will be returned. Other errors are possible too, and depend on what kind of filesystem the file is on.