code: def forward(self, model, model_kwargs, shape, z=None):
      pass
  
imports: import numpy
  import torch
  from einops import rearrange
  from tqdm import tqdm
  from nemo.collections.multimodal.modules.imagen.sampler.batch_ops import batch_div, batch_mul
  from nemo.collections.multimodal.modules.imagen.sampler.continuous_ddpm import GaussianDiffusionContinuousTimes
label_desc: Use image node_id 2 for calling the Sampler obj's underlying member method code with example usage: obj.forward(model, model_kwargs, shape, z) without return types