class_docstr: The abstract sparse optimizer.
  
  Note: dgl sparse optimizer only work with dgl.NodeEmbedding
  
  Parameters
  ----------
  params : list of NodeEmbedding
      The list of NodeEmbeddings.
  lr : float
      The learning rate.
docstr: A helper method to load param_groups from saved state_dict.
docstr_tok: ["A","helper","method","to","load","param_groups","from","saved","state_dict","."]
code: def _set_param_groups(self, groups):
      """A helper method to load param_groups from saved state_dict."""
  
imports: import abc
  from abc import abstractmethod
  import torch
  from ...cuda import nccl
  from ...nn.pytorch import NodeEmbedding
  from ...partition import NDArrayPartition
  from ...utils import create_shared_mem_array, gather_pinned_tensor_rows, get_shared_mem_array, pin_memory_inplace, scatter_pinned_tensor_rows
label_desc: Use image node_id 13 for calling the SparseGradOptimizer obj's underlying member method code with example usage: obj._set_param_groups(groups) without return types