code: def test_feature_flag(self):
      self.assertTrue(settings.fast_pred_var.is_default())
      self.assertFalse(settings.fast_pred_var.on())
      with settings.fast_pred_var():
          self.assertFalse(settings.fast_pred_var.is_default())
          self.assertTrue(settings.fast_pred_var.on())
      with settings.fast_pred_var(False):
          self.assertFalse(settings.fast_pred_var.is_default())
          self.assertFalse(settings.fast_pred_var.on())
  
file_path: gpytorch/test/test_settings.py
imports: import unittest
  import torch
  from gpytorch import settings
  from gpytorch.test.base_test_case import BaseTestCase
label_desc: Use image node_id 1 for calling the TestSettings obj's underlying member method code with example usage: obj.test_feature_flag() without return types