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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 get_state_paths(cls, impl, working_dir):
 """ Get the paths to the relevant db files to back up """

        return super(BlockstackDB, cls).get_state_paths(impl, working_dir) + [
                os.path.join(working_dir, 'atlas.db'), 
                os.path.join(working_dir, 'subdomains.db'),
                os.path.join(working_dir, 'subdomains.db.queue')
            ]