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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add(self, path, compress=None):
 """Add `path` to the MAR file. If `path` is a file, it will be added directly. If `path` is a directory, it will be traversed recursively and all files inside will be added. Args: path (str):
 path to file or directory on disk to add to this MAR file compress (str):
 One of 'xz', 'bz2', or None. Defaults to None. """

        if os.path.isdir(path):
            self.add_dir(path, compress)
        else:
            self.add_file(path, compress)