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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 _iter_full_paths(path_list):
 """ Iterates over all paths that are in a directory and its subdirectory, returning fully-specified paths. """

    for path in path_list:
        if not os.path.isdir(path):
            full_path = os.path.realpath(path)
            yield path
        else:
            for root, dirs, filenames in os.walk(path):
                for filename in filenames:
                    full_path = os.path.realpath(os.path.join(root, filename))
                    yield full_path