def _val_from_env(self, env, attr):
        val = os.environ[env]
        if attr in ('rules', 'exclude_rules'):
            return self._rules_from_env(val)
        elif attr == 'priority':
            return dict(self._priority_from_env(val))
        elif attr == 'wait_command':
            return int(val)
        elif attr in ('require_confirmation', 'no_colors', 'debug',
                      'alter_history'):
            return val.lower() == 'true'
        elif attr == 'history_limit':
            return int(val)
        else:
            return val
List the versions available for the given function.
dataset/ETHPy150Open nvbn/thefuck/thefuck/conf.py/Settings._val_from_env--crossover with--dataset/ETHPy150Open saltstack/salt/salt/modules/boto_lambda.py/list_function_versions