code: def __call__(self, n_samples, rand=None):
      idx = default(
          rand,
          torch.randint(0, self.num_idx, (n_samples,)),
      )
      return self.idx_to_sigma(idx)
  
file_path: generative-models/sgm/modules/diffusionmodules/sigma_sampling.py
imports: import torch
  from ...util import default, instantiate_from_config
label_desc: Use image node_id 3 for calling the DiscreteSampling obj's underlying member method code with example usage: obj.__call__(n_samples, rand) and returns: self