def __init__(self, groups=None):
        super(GroupedRequirements, self).__init__(NamedRequirements)
        self.groups = groups or self.default_groups
        self.filename = None
        self.create_default_groups()
def close_log_streams(self):
        """ Closes all log_stream streams. """
        while self._logging_handlers:
            self._logging_handlers.pop().close()