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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 _filter_config(self, config, fields=None):
 """ Filter sensitive details like passwords from a configuration dictionary. """

        filter_fields_default = [
            'bind_password',
            'connection'
            ]

        filter_fields = fields or filter_fields_default
        return dict(
            map(
                lambda key: (key, '<hidden>' if key in filter_fields else config[key]),
                config.keys()
                )
            )