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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 of_directory(directory: str, root_directory: str = None) -> dict: """ Returns a dictionary containing status entries recursively for all files within the specified directory and its descendant directories. :param directory: The directory in which to retrieve status information :param root_directory: Directory relative to which all file status paths are related. If this argument is None then the directory argument itself will be used. :return: A dictionary containing status information for each file within the specified directory and its descendants. The keys of the dictionary are the relative path names for each of the files. """


    glob_path = os.path.join(directory, '**/*')
    root = root_directory if root_directory else directory
    results = filter(
        lambda result: (result['modified'] != -1),
        [of_file(path, root) for path in glob.iglob(glob_path, recursive=True)]
    )
    return dict([(result['path'], result) for result in results])