def get_add_files_command(self, *filenames):
raise NotImplementedError()<EOL>
Get the command to include added and/or removed files in the working tree in the next commit.

:param filenames: The filenames of the files to include in the next
                  commit (zero or more strings). If no arguments are
                  given all untracked files are added.
:returns: A list of strings.

This method needs to be implemented by subclasses.