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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 _from_cfg(self, cfg):
 """ Initialize CFBlanket from a CFG instance. :param cfg: A CFG instance. :return: None """


        # Let's first add all functions first
        for func in cfg.kb.functions.values():
            self.add_function(func)

        self._mark_unknowns()