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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 _settings_checker(self, required_settings=None, accept_none=True):
 """ Take a list of required _settings dictionary keys and make sure they are set. This can be added to a custom constructor in a subclass and tested to see if it returns ``True``. :arg list required_settings: A list of required keys to look for. :arg bool accept_none: Boolean set to True if None is an acceptable setting. Set to False if None is not an acceptable setting. :returns: * bool ``True`` if all required settings exist, OR * str <key name> for the first key missing from _settings. """

        if required_settings is not None:
            for keyname in required_settings:
                if keyname not in self._settings:
                    return keyname
                if accept_none is False and self._settings[keyname] is None:
                    return keyname
        return True