class_docstr: Reduce scatter the input from the model parallel region.
class_docstr_tok: ["Reduce","scatter","the","input","from","the","model","parallel","region","."]
code: def backward(ctx, grad_output):
      return _gather_along_first_dim(grad_output)
  
imports: import torch
  from megatron.core.parallel_state import get_tensor_and_expert_parallel_group, get_tensor_model_parallel_group, get_tensor_model_parallel_rank, get_tensor_model_parallel_world_size
  from .utils import split_tensor_along_last_dim
label_desc: Use image node_id 3 for calling the _ReduceScatterToSequenceParallelRegion obj's underlying member method code with example usage: obj.backward(ctx, grad_output) and returns: _gather_along_first_dim