content: from typing import *
  
  
  class ClassifierFreeGuidanceSamplerMixin:
      """
      A mixin class for samplers that apply classifier-free guidance.
      """
  
      def _inference_model(self, model, x_t, t, cond, neg_cond, cfg_strength, **kwargs):
          pred = super()._inference_model(model, x_t, t, cond, **kwargs)
          neg_pred = super()._inference_model(model, x_t, t, neg_cond, **kwargs)
          return (1 + cfg_strength) * pred - cfg_strength * neg_pred
  