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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 directory(cls, prefix=None):
 """ Path that should be used for caching. Different for all subclasses. """

        prefix = prefix or utility.read_config().directory
        name = cls.__name__.lower()
        directory = os.path.expanduser(os.path.join(prefix, name))
        utility.ensure_directory(directory)
        return directory