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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 apply_flat(self, config, namespace_separator='_', prefix=''):
 # type: (Dict[str, Any], str, str) -> None """Apply additional configuration from a flattened dictionary This will look for dictionary items that match flattened keys from base_config and apply their values on the current configuration object. This can be useful for applying configuration from environment variables and flat configuration file formats such as INI files. """

        self._init_flat_pointers()
        for key_stack, (container, orig_key) in self._flat_pointers.items():
            flat_key = '{prefix}{joined_key}'.format(prefix=prefix, joined_key=namespace_separator.join(key_stack))
            if flat_key in config:
                container[orig_key] = config[flat_key]